Chapter VIII
Field Artillery, Tanks, Chemicals, and Smoke

Section		Page
I.	Field artillery	173
II.	Tanks	181
III.	Chemicals	184
IV.	Smoke	187

Section I
Field Artillery

Par.
801.	Field artillery in landing operations	173
802.	Types of field artillery	174
803.	Landing characteristics of field artillery	174
804.	Organization for landing	175
805.	Ammunition supply	175
806.	Motor transportation	175
807.	Assignment of field artillery	176
808.	Landing diagrams	176
809.	Debarkation plans	178
810.	Preparation of artillery units for debarkation	178
811.	Coordination of field artillery and naval gunfire	178
812.	Execution of fires	180
813.	Spotting planes	180
814.	Initial firing positions	180
815.	Protection of artillery against ground and air attack	181
816.	Support of advance inland	181

801. Field artillery in landing operations.--

     1. The employment of field artillery in the early stages of a landing operation differs from that of ordinary land warfare in the following essential features:

        1. In land warfare field artillery fires all preparatory and supporting fires. In a landing operation, all fire is executed by ships' guns until field artillery is ashore and is prepared to reinforce the ships' fire or take over certain fire missions.

        2. Due to difficulties in transporting and landing guns and ammunition, the amount of field artillery available in a landing operation will usually be less than in a land warfare operation on a corresponding scale. This factor may require ships' guns to continue on certain fire missions during all or a large part of the operation. Careful coordination of field artillery and ships' gunfire is required.

        3. On land, field artillery can usually go into position anywhere along its route and open fire as soon as it comes within range. In a landing operation, the initial movement is by boat, and field artillery must reach the beach before it can go into action. This factor, together with the necessity of reinforcing or relieving naval guns at the earliest possible time, makes it necessary to employ field artillery in a landing operation with greater boldness than in land warfare. However, as field artillery is particularly vulnerable to direct fire from machine guns and other infantry weapons, it may often prove disastrous to land the guns or howitzers before the infantry has had an opportunity to make the landing beach reasonably secure from such fire. Some provision as to the time of landing of artillery which will reconcile the above factors should, therefore, always be made.

        4. In offensive operations on land, field artillery can coordinate its fire with the advance of the infantry at the beginning of the attack by means of the line of departure, and when batteries displace forward to follow the progress of the attack, they can utilize fire data obtained from rear batteries. In a landing operation, the field artillery goes into action after the attack is well underway, requiring the most careful planning and coordination for the prompt execution of close supporting fires without danger to friendly troops.

        5. Due to the impracticability of exercising centralized control of artillery units throughout the periods of embarkation, debarkation, and landing, the bulk of the field artillery, in the movement overseas and during the initial phases of a landing operation, will usually be attached to

infantry units (brigades, regiments, or battalions). This necessarily reduces flexibility in the utilization of artillery fires and makes more difficult the concentration of a number of batteries on important objectives. As soon as the situation on shore permits, field artillery units should revert to the command of artillery battalion, regimental, or brigade commanders.
6. In the early phases of a landing operation, field artillery units will have little if any motor transportation available on the beach. This will necessitate the movement of guns, equipment, and ammunition, and the laying of wire, largely by hand. As hand displacement of guns and ammunition is seldom practicable for the distances necessary for any appreciable tactical advantage, such hand displacement will usually be limited to placing the weapons in firing positions in the vicinity of their landing beach.
2. The above considerations are discussed in more detail below.
802. Types of field artillery.--

     1. Light artillery.--Light artillery includes all guns and howitzers of 105-mm caliber (4.13 inches), or smaller. The following are the most suitable light artillery weapons for employment in a landing operation, listed in the order of desirability:

        75-mm pack howitzer.
        3-inch mountain guns.
        75-mm gun.

     2. Medium artillery.--Medium artillery includes the 155-mm howitzer. This weapon is too heavy for use in the early phases of a landing operation, but once landed, could be used to advantage in later attacks on shore.

     3. Heavy artillery.--Heavy artillery includes the 155-mm guns, and all guns and howitzers of larger caliber. Heavy artillery is used principally in base defense, but the 155-mm gun may under favorable conditions be landed sufficiently early to be utilized in the later phases of an offensive operation.

     4. Antiaircraft artillery.--

        1. Although not considered field artillery, the 3-inch antiaircraft guns and their complementary [.]50-caliber antiaircraft machine guns are the most suitable antiaircraft weapons for the type of operations under consideration. While intended primarily for base defense, these weapons may be utilized in offensive operations to furnish antiaircraft protection to rear establishments and, in some situation when terrestrial targets are within range, to augment the light artillery on certain missions.

        2. Antiaircraft gun batteries are designed for protection against high-altitude bombing and, after establishment on shore, may be coordinated with any antiaircraft guns on ships in the area.

        3. Antiaircraft machine guns (50 caliber) are for protection of rear establishments against low-flying aircraft. Some of these machine guns should be landed with the leading boat groups and set up near the beach to protect rear echelons of our field artillery and the landing of succeeding troops, supplies, and equipment.

803. Landing characteristics of field artillery.--The weight and dimensions of the various types of weapons and vehicles used by the artillery of the Fleet Marine Force are given in "Logistic Data, U.S. Marine Corps".

804. Organization for landing.--

     1. Light artillery.--

        1. In order to permit flexibility in the assignment and landing of light artillery, it is desirable that complete gun sections be embarked in separate boats and the boats transporting a battery organized into a boat division. This will permit sections or batteries to be attached to boat groups, transporting infantry units, or the artillery battalion to be landed intact. In either case, the artillery boat divisions, after leaving the line of departure, may be made to cruise independently of those carrying the infantry and thus provide for landing at the most propitious time; that is, as soon as the landing beach is reasonably secure from the direct fire of enemy weapons.

        2. Artillery liaison details precede their units to the beach. They usually go in the same boats as the headquarters of the infantry unit to which they are attached, or are supporting. Liaison details should be prepared to furnish their organizations immediately upon landing with the latest details pertaining to the situation.

        3. Reconnaissance details should be landed sufficiently early to permit them to carry out the following duties prior to arrival of the gun sections: Selection of locations for firing positions, observation posts, and other artillery installations; routes from the beach to same, and the point for landing each section. It is desirable that reconnaissance details be provided a separate boat, not only to permit changes in the assignment of artillery units by boatloads, but also to facilitate the guiding in of waiting artillery boats after decision has been made as to the point and time of landing.

     2. Heavy and antiaircraft artillery.--

        1. With the exception of some [.]50-caliber antiaircraft machine guns landed for early protection of the landing beach, the heavy and antiaircraft artillery will not be landed until an adequate beach head has been secured and all of the infantry and field artillery are ashore. Lighters, barges, or large boats transporting heavy and antiaircraft artillery will usually operate separately.

        2. Antiaircraft [.]50-caliber machine guns and ammunition which are to land with the leading troops should be assigned to the boat group with which they are to move, and given a specific place in the formation. These guns will seldom precede the landing of the battalion reserves.

805. Ammunition supply.--

     1. The landing and movement inland of an adequate ammunition supply presents a more serious problem than that of guns and howitzers. A 75-mm. pack howitzer, for example, can fire twice its own weight in ammunition every hour. In the assignment of boat spaces, therefore, allowance must be made for an adequate ammunition supply.

     2. A unit of fire for any artillery unit is the average daily expenditure of the unit during several days' combat. The expenditure of ammunition is not uniform, and from two to three units of fire may be expended daily during the initial stages of a landing operation. A unit of fire for light artillery is 300 rounds per gun or howitzer, and will last from 2 to 3 hours' actual firing.

     3. At least two-thirds of one unit of fire should be landed with each battery; the remaining third to follow within 1 hour. It is desirable that this ammunition be distributed so that each gun section will have its quota loaded with it in the same boat. Assuming that the ammunition is HE, and will be carried ashore unboxed but in fiber containers, this would require about 50 boat spaces per section; approximately 59 boat spaces being required for the section and its whole unit of fire. Sufficient beach and shore party personnel should be available to dump the ammunition on the beach, so that the battery personnel may be utilized for getting the guns promptly into action.

     4. Provision should be made to continue to land additional ammunition in time to insure batteries maintaining an appropriate rate of fire, making due allowance for losses en route and in the destruction of dumps ashore.

806. Motor transportation.--

     1. Light artillery.--If boat space is available, it is desirable to land at least some of the ammunition carts, tractors, and trailers with, or close behind, the firing batteries. These vehicles will be of great assistance in moving guns and howitzers into position and transporting ammunition from the beach to firing positions. For early movements by hand, see paragraph 801a (6), above.

     2. Heavy and antiaircraft artillery.--Except in case of early landing of some [.]50-caliber antiaircraft machine guns (see pars. 802d and 803b (2)) tractors should be landed with, or before, the firing sections so that the tractors will be available to haul the guns and other matériel from

lighters or barges to firing positions. Trailers for handling ammunition should be landed as soon as practicable.
807. Assignment of field artillery.--

     1. 1. When an artillery unit is placed temporarily under the direct command of an infantry commander, it is designated as "attached" artillery. While so attached, the infantry commander gives orders direct to the commander of the artillery. Depending upon the period for which attached, such orders may cover the embarkation, debarkation, landing, and the tactical employment of the artillery on shore.

        2. An "accompanying gun" is a gun or howitzer attached to a subordinate infantry unit for the purpose of accompanying the assault echelons in the landing and advance inland. Such guns are vulnerable to enemy fire and the ammunition supply is difficult to maintain. They should not be landed in the face of direct fire. After the fire fight in the vicinity of the beach, accompanying guns may be directed to remain in position and gather fire data for the remainder of the battery which is to land and join them later.

     2. Supporting artillery is that which executes fire missions in support of specific infantry units but remains under the command of the next higher artillery commander. It is classified as general or direct support as follows:

        1. General support artillery executes the fires directed by the commander of the unit to which it organically belongs or is attached. It fires in support of the operation as a whole, rather than in support of a specific subordinate infantry unit.

        2. Direct support artillery is assigned the task of executing the fires requested by a specified subordinate infantry unit. Requests for fires are made direct upon the supporting artillery by the infantry unit being supported.

     3. 1. Field artillery operates at its highest efficiency when the fire of all batteries is coordinated and controlled by a single commander. This should always be the ultimate aim of all planning.

        2. In a landing operation, however, light artillery battalions will usually be attached to infantry regiments for the embarkation, debarkation, landing, and tactical employment ashore during the initial phases of the operation. The infantry regimental commander may attach sections, platoons, or batteries to assault battalions, or he may employ the artillery battalion as a unit. In the latter case, all batteries may be kept in general support, or certain batteries may be put in direct support of assault battalions.

        3. The attachment of batteries to assault infantry battalions is applicable under the following conditions:

           When such decentralization of control is necessary in order to provide for the timely debarkation from ships and movements to the beach.

           When there is no time to install means for immediate centralized control on the beaches at the time artillery support first becomes necessary.

           When it is the only sure way of providing timely artillery support for the battalion when it must operate independently, either because of landing on a separate beach or otherwise becoming isolated from other friendly troops.

     4. Heavy artillery will usually be in general support.

808. Landing diagrams.--

     1. 1. Figure 1 illustrates an artillery battalion attached to an infantry regiment landing with two battalions in assault and one in reserve. One battery is attached to each assault battalion, and the artillery battalion (less two batteries) is held under control of the infantry regimental commander. The boats transporting each attached battery are organized into a boat division assigned to the boat group transporting the assault battalion. The boats transporting the remainder of the artillery battalion are also organized into a boat division which is assigned to the boat group transporting the reserve infantry battalion.

        2. Each assault battalion is landing with two companies in assault and one in reserve. The reserve rifle company usually lands behind the assault company most successful in its advance. As the boat group approaches the range of effective enemy fire, the boat division transporting the attached artillery, when practicable, should be maneuvered to avoid such fire by slowing up or stopping until it can proceed further on its course toward the beach with reasonable safety. As soon as the beach is considered sufficiently secure from enemy direct fire, and when directed by the infantry battalion commander, the battery should be brought in and landed. This may be accomplished by having the artillery reconnaissance officer contact the artillery boat division by signal or by messenger boat from the beach. (see par. 804a (3) above for duties of reconnaissance details.

Figure 1.--Artillery batteries attached to infantry battalions.

3. The boats transporting the reserve infantry battalion and the remainder of the artillery battalion should arrive at a designated area, usually in the vicinity of the control vessel, at about H plus 15 minutes. Here orders will be received from the infantry regimental commander concerning the point of landing, when to start, and the artillery support desired.

4. When the artillery battalion commander lands, the battery attached to the assault battalion landing on that beach should revert to his control as soon as practicable. The battery attached to the other assault battalion should revert as soon as the situation permits adequate control by the artillery battalion commander. This change in status is executed by orders of the infantry regimental commander.

5. Assignment of battery and battalion reconnaissance and liaison details to boats are also shown in figure 1.

2. 1. Figure 2 illustrates an artillery battalion attached to an infantry regiment landing in the same formation as is figure 1. One section of artillery, constituting an advance echelon of the firing battery, is attached to each assault battalion. The boat transporting this gun section is assigned to the boat division transporting the reserve rifle company and battalion headquarters of each assault battalion. A section so attached should be detailed from the battery which is to support that battalion.

   2. The boats transporting the artillery battalion (less the detached sections) may be organized into a separate boat group or may be assigned to the boat group transporting the reserve infantry battalion. The boats proceed to a designated area where orders are received from the infantry regimental commander as to the time and place of landing.

   3. The artillery battalion (less the two detached sections) may be landed intact in rear of the reserve infantry battalion on the beach where the greatest success has been achieved. In case of an equally successful landing on both beaches it may land one battery on one beach and the battalion, less a battery, on the other beach.

   4. For the execution of fire missions after landing, one battery may be placed in direct support of each assault battalion with the third battery in general support, or all three batteries, less detached sections, may be held in general support to fire as directed by the infantry regimental commander.

   5. Appropriate assignments of the artillery battalion liaison and reconnaissance details to boats are indicated in figure 2.
809. Debarkation plans.--Boat assignment tables, landing diagrams, and boat diagrams are prepared for artillery units in the same manner as prescribed in chapter IV for infantry units. Boats transporting an attached battery or section of artillery are included in the landing diagram of the boat group transporting the infantry unit to which attached.

810. Preparation of artillery units for debarkation.--

     1. Light artillery.--

        1. Light artillery units and 50-caliber antiaircraft machine guns that are to go ashore during the early phases of an operation should, in order to expedite the debarkation, stow guns and fire control and signal equipment near the place where the matériel is to be lowered into the boats. Ammunition should be kept in magazines until shortly before it is to be loaded in boats.

        2. Improvised davits and hand lines should be provided for lowering light equipment into boats. Ammunition and boxed articles should be placed in cargo nets ready for hoisting. Motor transportation should be serviced, slings hooked on, and made ready for hoisting.

        3. Frequent drills should be held in carrying out the above provisions. The time required for debarkation should be determined so that loading of artillery units may be coordinated with that of the infantry units with which they are to land.

     2. Heavy and antiaircraft artillery.--With the exception of some [.]50-caliber antiaircraft machine guns which may be landed earlier, the preparation of heavy and antiaircraft artillery units for debarkation will not begin until most of the infantry and light artillery units are unloaded. The preparation for debarkation is similar to that explained above for light artillery, except boats and lighters usually proceed to and from the beach independently, and the maintenance of an accurate time schedule is not as important.

811. Coordination of field artillery and naval gunfire.--

     1. The employment of field artillery fire and ships' gunfire must be closely coordinated, due consideration being given in the assignment of fire missions to the number, characteristics, powers, and limitations of the types of weapons available. (See pars. 542, 552c, and 731 for means of coordination.)

     2. Light field artillery batteries, immediately upon landing, should be assigned the mission of close support. As additional batteries are landed, they should progressively take over appropriate fire missions from ships' guns. Medium and heavy artillery will usually not be available;

or may be very limited in amount, particularly during the early phases of the operation, and it may be necessary for ships' guns to continue deep supporting, counterbattery, and interdiction fires for a considerable period of time.
3. All field artillery agencies, such as intelligence, liaison, and reconnaissance details, should give all information and assistance possible to ships' fire control parties ashore. Field artillery

Figure 2.--Howitzer sections attached to infantry battalions.

observation posts and communication installations should also be made available for ships' fire control parties.
4. It is desirable that artillery officers of the landing force, if available, be assigned to ships furnishing gunfire support. It is also desirable to assign field artillery officers, experienced as air observers, to planes detailed for spotting field artillery fire.
812. Execution of fire.--

     1. Artillery control line.--

        1. This is a line short of which the field artillery does not fire except on request of infantry commanders and beyond which the advance is supported by the bulk of the field artillery. Its introduction is often desirable in order to permit artillery to open fire immediately upon landing without danger to friendly troops.

        2. The position of the artillery control line is fixed after consideration of the probable position of the infantry at the time the artillery is ashore and in position to open fire. If suitable terrain features exist, the artillery control line should be located a safe distance beyond an infantry objective which can easily be defined and readily identified on the ground by both infantry and artillery. If no such natural features exist, the artillery control line should be located at such distance from the beach that the advanced infantry elements will not, in all probability, have reached the target area at the time it is estimated that the artillery will open fire.

        3. Main reliance must be placed in ships' gunfire and aviation for support of the attack until it reaches the artillery control line, as field artillery will not be in position to fire short of this line unless the attack is stopped or materially slowed down before the artillery control line is reached.

     2. Scheduled fires.--

        1. Targets should be selected from the control line inland and a time schedule prepared for fire on these targets according to the rate of advance specified by the infantry commander, usually from 25 to 50 yards per minutes, depending upon the terrain and expected battle conditions. In the absence of request from the infantry for other fires, artillery units, immediately upon going into battery, open fire on the selected targets and execute the prescribed scheduled fires.

        2. If desired, targets for scheduled fires may be selected without prescribing an artillery control line. The selection of the initial targets should be governed by the same considerations as the control line, as explained in subparagraph a, above.

     3. Fires short of artillery control line.--In case the attack is stopped or materially slowed down, field artillery should be prepared to place fire short of the artillery control line. This fire should not be delivered unless requested by infantry commanders on specific targets, or unless the artillery has reliable information of the exact location of its own front-line troops.

     4. Increasing the rate of advance.--In case only slight resistance is encountered and the attack progresses at a greater speed than that contemplated, the infantry commander may order the advance to continue beyond the artillery control line without awaiting for the prescribed hour. He should do this, however, only when he is sure the supporting artillery has received information as to the change in plans and is prepared to fire a safe distance beyond the artillery control line, this distance to be determined at the time according to the existing conditions.

813. Spotting planes.--In the early stages of a landing operation the infantry may not have gained sufficient ground by the time artillery lands to permit the establishment of suitable artillery observation posts. There will also be a lack of accurate information pertaining to the position of our own troops and to enemy positions and installations. For the above reasons, it is particularly important that observation planes make contact with batteries immediately upon landing for observation and spotting. Planes observers should be familiar with the schedule of fires prescribed for the artillery. (See 724d (2).)

814. Initial firing positions.--

     1. Prior to debarkation, tentative firing positions should be selected on all beaches where batteries may land. The tentative positions chosen should usually be near the landing beach, and where a short advance of the infantry will provide defilade from enemy direct fire. The first selections may have to be modified according to the progress of the attack, the nature of the terrain as developed by reconnaissance, enemy fire, and landing conditions found at the beach.

     2. It is advisable to avoid positions on the immediate beach, as this area will be congested and probably under well-directed enemy artillery fire. The proximity of the front lines, however, and the necessity of getting into action with all possible speed, combined with the difficulty of manhandling guns and ammunition for considerable distances, may necessitate selecting initial firing positions close to the beach.

     3. As soon as sufficient ground has been gained and motor transportation is available for handling ammunition, arrangements should be made for displacing batteries inland.

815. Protection of artillery against ground and air attack.--

     1. The superior knowledge of the terrain possessed by the defender, combined with the tendency of assault troops to pass beyond small enemy groups, will facilitate infiltration by the enemy and make mopping-up difficult for the attacker. Artillery also approaches closer to the enemy front lines in the early stages of a landing operation than in land warfare. Due to the above considerations and despite precautions taken to land it only after the beach is clear, artillery in the early stages of a landing operation will be particularly vulnerable to attack by small parties of the enemy, and must be prepared by training and equipment to protect itself against such attack both while en route and in position.

     2. Antiaircraft units may not be able to operate ashore in the early phases of the attack and artillery must be prepared to defend itself against low-flying attack planes. The early landing of some .50-caliber antiaircraft machine guns, as indicated in preceding paragraphs, should be provided for this purpose.

816. Support of advance inland.--In the support of the advance inland the employment of field artillery is much the same as in any land offensive, the principal difference being the possible shortage of motor transport and the consequent desirability of maintaining firing positions within a short haul from the beach.

Section II
Tanks

Par.
817.	Use of tanks in landing operations	181
818.	Methods of landing	181
819.	Assignment of tanks	181
820.	Preliminary reconnaissance	181
821.	Time of landing tanks	181
822.	Organization for landing	182
823.	Stowage of tanks and lighters aboard ship	183
824.	Preparations for debarkation	183
825.	Landing	183
826.	Action after landing	183

817. Use of tanks in landing operations.--

     1. The primary mission of tanks in the landing operation is to facilitate the passage of infantry through the immediate beach defenses by destroying enemy wire and machine gun defenses at or near the water's edge. They are particularly valuable in covering the flanks of the landing.

     2. In addition, tanks in adequate numbers should be provided to support the advance to the final objective. Their speed and maneuverability make them particularly effective for rapid exploitation.

818. Method of landing.--The most effective use of the tanks results when a special self-propelled tank landing craft or ship is provided which can keep up with the leading boats and permits the tank to run rapidly ashore under its own power as soon as the craft beaches.

819. Assignment of tanks.--In the initial phases tanks are normally assigned to assault battalions in accordance with the importance of the task assigned the individual battalion and the nature of the terrain. The distribution should be such as will provide for a heavy concentration of tanks against the more important objectives. During the advance inland tanks may be organized into separate task units for special operations.

820. Preliminary reconnaissance.--In order to select the best landings and routes inland, the most thorough preliminary reconnaissance possible should be made of beaches on which it is proposed to land tanks. Particular attention should be paid to surf conditions, depth of water, and obstacles to the passage of the tanks inland. Observation from aircraft and submarines, aerial photographs, maps, charts, and reports of marine patrols may be used to secure the desired information.

821. Time of landing tanks.--

     1. When the leading troops arrive at the beach, naval gunfire may be firing several hundred yards inland. Field artillery will not be landed and ready to fire in support of the advance for possibly 20 to 30 minutes, and aircraft must be largely depended

upon initially to deliver close supporting fires between the beach and the area being shelled by naval gunfire. It is during this phase of the operation that tanks will be of the most value, particularly where the number of planes for close support is limited.
2. In order to provide immediate support for the advance from the beach during the critical stage described above, tanks should be landed ahead of or with the leading troops.

3. When tank lighters are available, tanks should be assigned to the leading waves. Under these conditions tank weapons should be used to supplement the fire of boat guns.

4. Where landing conditions are known to be bad, tanks should be landed in the second or succeeding waves. Under these conditions, reconnaissance agents should be landed in the leading waves.
822. Organization for landing.--

     1. In order to permit flexibility in the landing formation, it is desirable, initially, to organize the boats or lighters transporting a tank platoon (five tanks) into a separate boat division. This division may operate as a unit or the individual boats or lighters may be later assigned to boat divisions transporting rifle units, depending upon the speed and type of the boat or lighter, landing conditions on the beach, routes of advance inland, and the proposed tactical employment ashore.

Figure 3.--Tank lighters in second wave.

Figure 3 shows a boat division transporting a tank platoon operating as a unit in the second wave. Figure 4 shows tank lighters assigned to boat divisions transporting rifle platoons in the leading wave.

Figure 4.--Tank lighters in leading wave.

2. Boats and lighters transporting tanks will usually be included in the boat assignment table and landing diagram of the boat group transporting the infantry battalion to which the tanks are attached. If at the time landing diagrams are prepared it is not definitely known to which infantry battalions tanks will be attached, orders may be issued later covering the task assignment of the boat division of tank lighters and its position in the formation of the boat group to which attached.
823. Stowage of tanks and lighters aboard ships.--

     1. In order that the lowering of tanks may not delay the debarkation, it is desirable that the tanks of a platoon be stowed in two or more holds.

     2. Tank lighters or boats should be stowed so that they may be lowered and loaded in time to leave with, or even ahead of, the leading wave, depending upon their speed.

824. Preparations for debarkation.--

     1. In the preparation of debarkation data, the time of loading boats or lighters transporting tanks should be carefully ascertained.

     2. Prior to the hour set for lowering boats, tanks should be run under the hatches, slings hooked on, and the full allowance of ammunition loaded. Prior to lowering, or immediately thereafter, gasoline tanks should be filled, engines tested, and the tanks made in all respects ready for immediate entry into combat.

825. Landing.--Tank engines are started when well offshore and all preparations made for landing. As soon as the lighter or boat beaches, ramps are rigged, if necessary, and the tank landed with all possible speed.

826. Action after landing.--The tactics of tanks after landing are much the same as those of ordinary land warfare. The plan of attack will prescribe important objectives against which the tanks will be concentrated, but tank commanders should use great initiative in attacking enemy weapons, particularly those along and on the flanks of the beach which are endangering the landing or advance inland. Tanks will usually be attached to appropriate rifle units.

Section III
Chemicals

Par.
827.	Use of chemicals	184
828.	Description of chemical agents	184
829.	Employment of chemicals by the attacker	184
830.	Individual protection	185
831.	Collective protection	185
832.	Ammunition requirements	185

827. Use of chemicals.--

     1. The increasing publicity given to chemical warfare protection and the numerous drills held by both the military and the civilian population, coupled with the preparation and installation of shelters for protection against chemical attack, indicate that most nations anticipate the use of chemical agents by their probable enemies. Under such conditions it must be assumed that any attempted landing operations will be met by the use of all available weapons, including chemical agents.

     2. This section deals only with chemical warfare as applied to landing operations. For details and general doctrine see Service Chemicals, U.S. Navy.

828. Description of chemical agents.--

     1. In this section chemical agents are treated collectively under their four general classifications according to physiological effect on the human body. For the employment of smoke, see section IV of this chapter.

     2. The following table shows the four general classifications of suitable war agents and a brief description of each classification:

        Classification	Example	Munition	Physiological action	Principal tactical use
        Vesicants	Mustard (HS)	Bombs, shell, airplane spray.	Blisters and sores on skin and in lungs.	To produce casualties in personnel and deny areas to enemy.
        Lung irritants	Phosgene (CG)	Shell (6 inches and larger) and cylinders.	Burns lungs.	To produce casualties in personnel.
        Sternutators (irritant smokes).	Adamsite (DM)	Candles, bombs, and destroyers.	Coughing, sneezing, and vomiting.	To harass personnel.
        Lacrimators	Tear gas solution (CNS).	Bombs grenades, shell, airplane spray.	Lacrimation, skin itching, vomiting.	Do.

     3. In addition to the above-mentioned classes of agents, white phosphorus (WP), although usually classed as a smoke producer, may be used in shell or airplane bombs for producing casualties in personnel, and as an incendiary.

829. Employment of chemicals by the attacker.--

     1. The employment of chemical agents by the attacker during a landing operation will be limited by two important factors, namely:

        1. No employment of chemical agents should be allowed to interfere with the movement of the attacking troops, either while they are on the water or immediately after landing. For example, even a light concentration of a nonpersistent lacrimator to the windward of landing troops may force them to wear the gas mask. This wearing of the mask handicaps the attacker much more than it does the defender.

        2. Persistent agents, such as vesicants, should not be laid on any shore area, the use of which may later be necessary to the landing force, for its operations on shore during the period of persistence of the particular agent.

     2. Subject to the above restrictions, aircraft may be employed before, during, and after the ship to shore movement of troops, for the following tasks:

        The denial of use of hostile airdromes and landing fields to the enemy by bombing and spraying with a persistent vesicant.

        The silencing of shore batteries, particularly large-caliber coast-defense guns and mortars, by bombing and spraying with all types of chemical agents.

        The extension of the deep supporting fires from ships' guns by bombing and spraying areas known to be occupied by the enemy for casualties and harassment of personnel. Nonpersistent sternutators and lacrimators are suitable for this task.

Although most of the above classes of agents are called nonpersistent, the length of time which must elapse before their complete dissipation depends on the conditions of wind, weather, and terrain.

The production of casualties in, and delay in the movement of, enemy reserves located in rear areas. This may be accomplished by bombing and spraying with any type of agent.

The denial of the use of certain bridges, fords, passes, roads, and larger areas to the enemy by bombing or spraying with vesicants or other sufficiently persistent agents.

The production of casualties, and the denial of certain areas to the enemy, by setting fires to dry brush, canefields, and grass, by bombing with white phosphorous. As this agent produces great quantities of smoke, it should be employed only when complete visibility is not necessary for the conduct of other more important operations.

3. If chemical projectiles are available for naval guns, nonpersistent lacrimators and possibly sternutators may be included at the beginning of a bombardment, for harassment of personnel. Persistent agents may be used to advantage against large-caliber, coast-defense gun positions, and isolated areas not needed later for the operation of our own forces. The smaller calibers are usually the most effective for firing persistent agents.

4. Except for the light concentrations necessary to harass the enemy and force him to wear masks, it should be remembered that, in order to be effective, chemicals must be laid down in heavy concentrations.
830. Individual protection.--

     1. 1. In a landing operation the employment of all types of chemicals by the defender is particularly applicable, and he may be expected to continue chemical attacks throughout the operation. These chemical attacks may include airplane spraying of transports and small boats with vesicants and lacrimators, airplane bombing with white phosphorous; the releasing of clouds of lung irritants, sternutators, and lacrimators from the shore line against landing boats; the releasing of vesicants on the surface of the water adjacent to beaches; the contamination of certain beaches, islands, peninsulas, and interior areas by a persistent vesicant; and the employment of all types of agents against the beach head during the time of greatest congestion of troops and matériel following a successful landing.

        2. Protective measures, therefore, assume an important part in the planning of any ship to shore movement. At the same time, these protective measures must not be such as to prevent the various operations being carried out or to cause undue delay. Complete protection of men and matériel against chemical attacks is no more to be expected than complete protection against other weapons.

     2. A high degree of individual protection may be provided by gas masks, impregnated or impermeable clothing, protective gloves, and protective shoes. If an adequate supply of al the above articles is not available, gas masks, at least, must be issued to all personnel, and protective clothing, gloves, and shoes should be provided for those who are most likely to be exposed to the spray of liquid vesicants and to those detailed for decontamination work.

831. Collection protection.--

     1. In addition to the above precautions for the protection of the individual, certain measures must be taken for group or collective protection. These measures include--

        Reconnaissance;
        Planning the scheme of maneuver to avoid gases;
        General organization for protection;
        Special protection of men and matériel in boats; and
        Decontamination of beaches and routes inland.

     2. Reconnaissance.--Every effort should be made to ascertain by preliminary reconnaissance or demonstrations of the enemy plan for the utilization of chemicals, so that the most effective protective measures may be initiated in advance, or the contaminated areas avoided. (See ch. IV, sec. VI, Reconnaissance Patrols.)

     3. Scheme of maneuver.--In planning the scheme of maneuver every effort should be made to avoid areas known or suspected of being contaminated, or which are likely to be subjected to gas attack. Lacking definite information, open beaches and high, open, wind-blow terrain is the safest; conversely, protected beaches, wooded areas, ravines, hollows, and defiles are the most favorable for the effective use of chemicals.

4. General organization.--

   1. Officers trained in chemical warfare should be assigned all ships, regiments, and battalions, and trained noncommissioned officers to all companies. Their general duties are to take charge of chemical warfare protective matériel and to give technical advice. (See ch. VI, Service Chemicals, U.S. Navy.)

   2. Gas sentries trained to recognize various gases by smell should be posted whenever there is likelihood of a chemical attack, so that an alarm may be promptly given.

   3. Standing orders covering procedure for protection against chemical attacks should be issued.

   4. Alarm systems, both general and local, should be installed. Alarms should be made by sound, such as the sounding of a bell, klaxon, whistle, or gong. Advance warning of a chemical attack at sea may be obtained by signal from aircraft or other ships.

   5. Materials for decontamination should be kept available for use in all ships and boats and the methods of using them disseminated to all concerned.

5. Protection of men and matériel in boats.--

   1. Security measures against chemical attacks for men and matériel in small boats include local control of the air by friendly aircraft, protective covering for boats, warning of attack by gas sentries, development of the maximum antiaircraft fire, and decontamination measures.

   2. Close-fitting tarpaulins of oilcloth or canvas should be made a part of the equipment of each boat to protect the occupants from liquid spray. When possible, this covering should be furled thwartships with one edge made fast just abaft the boat gunners and ready to be quickly spread to the rear over the heads of the troops. All equipment and munitions not likely to be used until the boats reach the beach should be covered with separate mustard proof coverings. Snug-fitting canvas tarpaulins while not mustardproof, offer considerable protection. All food not in airtight containers is subject to contamination.

   3. At least one gas sentry should be detailed in each boat to watch for and give warning of a chemical attack, and sufficient men should be assigned to adjust the tarpaulin covering on short notice.

   4. While a quick and complete decontamination of the skin and equipment of personnel and the interior of boats is doubtful, the effects of an attack by spray of a liquid vesicant can be alleviated if each boat is supplied with a quantity of decontamination material. A thorough scrubbing with soap and fresh water will reduce the severity of mustard burns; scrubbing with a rag soaked in kerosene, gasoline, or even lubricating oil is also a great aid. After such scrubbing the application of a weak solution made of chloride of lime and water (not stronger than 50 to 50 by weight) will further counteract the effects of the mustard. It should be borne in mind, however, that decontamination measures must not be allowed to interfere with the operation of the boats or the fire of the weapons therefrom.

6. Decontamination of beaches and routes inland.--

   1. If, when the small boats approach the beach, pools or globules of oily liquid vesicant are discovered floating on the surface of the water, every effort should be made to avoid them, as troops wading through such contaminated water are very likely to become casualties within a short time. Such vesicants are more likely to be found on still water than in running water or surf. When it is necessary to land through water so contaminated, the best protection is afforded by shallow-draft landing boats capable of running well up on the beach and thus permitting the troops to disembark directly onto the beach. Beating the water with oars, and backing with the engine may help in a measure to dissipate the liquid floating on the surface or lessen the effects through partial hydralization.

   2. Sufficient material, such as chloride of lime or CC No. 1 solution, should be landed to provide for decontamination of vital positions on the landing beach immediately after the landing of the assault troops, and sufficient men of the shore parties should be properly equipped with protective clothing to do this work.

   3. Although decontamination of large areas may be impracticable, this work may well be undertaken at the landing points for succeeding troops, in areas necessary for certain limited activities on the beach and on roads or trails leading inland to ungassed areas.

   4. Large signs should be brought ashore by members of the shore parties and set up at proper places to warn personnel of gassed areas and indicate alternate routes.

   5. As soon as practicable after the landing, decontamination stations should be improvised for the purification of clothing and equipment. (See Service Chemicals, U.S. Navy.)
832. Ammunition requirements.--

     1. 1. Table A shows aircraft chemical ammunition requirements for each of several tasks.

2. Table B shows ammunition requirements for chemical shell necessary to produce an effective density in each 100-yard square of target area. The requirements shown are based on three representative chemical agents fired by 75- and 155-mm guns or howitzers.

3. Table C shows the weights of the three representative chemical agents in the 75- and 155-mm shell.

4. Ammunition requirements for other calibers can be computed for mustard and CN solution from tables B and C by plotting the figures in these tables on a piece of cross-section paper, using the "X" coordinate for the number of shells required and the "Y" coordinate for the weight of chemical in each shell. After the points are thus established for the 75- and 155-mm, the points should be connected by a line. From this line, or a continuation thereof, the required number of shells of any given chemical charge can be obtained. At least 368 pounds of phosgene, released within 2 minutes, is required for each 100-yard square of target.

TABLE A.--Ammunition requirements for aircraft

30-pound chemical bomb filled with 7.4 pounds mustard (HS):1
	Bombs per square (100 by 100 yards) of target area	15
	Bombs per 100 linear yards of occupied road	5
	Bombs per 100 linear yards of road for interdiction	10
Nonpressure tank apparatus for planes, each tank containing approximately 15 gallons of liquid mustard or other chemical agent. Planes are normally equipped with two wing tanks. Figures given below are for one tank only. The length of the area may be doubled by release in turn, or the width of the area may be increased 50 percent by simultaneous release:
	Character of target	Area effectively covered
	Unprotected personnel	800 by 500 yards
	Equipped with mask only, or poorly trained	800 by 250 yards
	Fully equipped and well trained	800 by 75 yards

¹ (1) Ammunition requirements remain the same for bombs containing an equal weight of any other liquid filler. (2) Corrections for weather and terrain in the case of mustard: Temperatures below 50° increase requirements 25 percent. Except for point targets, reduce quantities 50 percent when targets are wooded.

TABLE B.--Ammunition requirements for chemical shell necessary to produce effective density in each 100-yard square of target

Caliber	Mustard1	CN solution2	Phosgene3
75-mm (2.95 inches)	80	5
155-mm (6.1 inches)	17	2	23

¹ No time limit in firing. Persistent for several days.
² Rounds per hour.
³ Fired within 2 minutes.

Corrections for weather and terrain applicable to the above table: Mustard: Temperature below 50°, increase requirements 25 percent. Except for point targets, reduce quantities 50 percent when targets are wooded. CN solution: Temperature below 50°, increase requirements 25 percent.

Figures indicate number of rounds which must strike in the target area. Rounds necessary to cover inaccuracies in fire, due to range, dispersion of guns, etc., must be added.

TABLE C.--Chemical content of field artillery shell

Caliber	Approximate weight of content of chemical shell, in pounds
	Mustard	CN solution	Phosgene
75-mm (2.95 inches)	1.3	1.5
155-mm (6.1 inches)	11.0	13.0	11.1

Section IV
Smoke

Par.
833.	Use of smoke	188
834.	Means of projecting smoke	188
835.	Smoke from aircraft	188
836.	Smoke from destroyers	189
837.	Smoke from projectiles	192
838.	Smoke from boats	193
839.	Illustrations; smoke laying by planes	193

833. Use of smoke.--

     1. Smoke may be used in connection with a landing for the following purposes:

        To reduce the effectiveness of enemy fire.
        To conceal the point of the main attack.
        To increase the effect of a demonstration or secondary landing.
        To simulate or camouflage a chemical attack.

     2. 1. The effective use of smoke to cover a landing requires special skill and training on the part of those charged with laying it, and the closest degree of coordination between aircraft, supporting vessels, and landing boats, together with an accurate knowledge of the effect of various weather conditions. (See ch. V, sec. IV for coordination.)

        2. It must also be realized that smoke blinds the attacker as well as the defender, precludes the use of certain planes and ships for other tasks, increases the difficulties of navigation of ships and boats, curtails the use of signals from boats and the shore, and, when projected from aircraft tanks, may require ships and boats to suspend fire while it is being laid. As smoke often obscures aiming points and targets on the beaches, direct fire by supporting ships, particularly inshore ships, is not only greatly handicapped but often precluded.

        3. The effective use of supports and reserves depends upon securing immediate information of the success or failure of preceding units. This information is preferably obtained by direct observation, which will usually be rendered difficult or impossible by the use of smoke.

     3. It should be realized that the effective laying of smoke is to a great extent indeterminable. The decision as to whether or not it will be used requires consideration as to the probability of laying an efficient screen, and a careful balancing of the benefits expected from the smoke against the supporting value of weapons or troops it displaces or renders less effective. The following factors will largely govern the final decision: The availability of vessels and planes for laying smoke, probable weather conditions, the number and type of supporting vessels available for use in the operation, and navigational considerations. In this connection, it should be noted that while firing into a smoke-covered area reduces the accuracy of the fire, tests have demonstrated that the reduction in accuracy is many times greater when firing from a smoke-covered area.

834. Means of projecting smoke.--Smoke to cover a landing may be projected by the following means:

     Aircraft--tanks or bombs.
     Destroyers.
     Shell fired from guns, mortars, or howitzers.
     Small boats--tanks, candles, bombs, or floats.

835. Smoke from aircraft.--In connection with the laying of smoke screens by aircraft tanks and bombs, see illustration in paragraph 839, and chapter VI, section V, Aerial Operations During Approach to Beach.

836. Smoke from destroyers.--

     1. Destroyers may be used to screen the vessels of the attack force and the distant approach of the landing boats. A dense smoke which tends to cling to the surface of the water should be used. Where wind conditions are favorable destroyers may also be used to blanket the beach to cover the landing of troops, as indicated in figure 5.

Figure 5.--Destroyers blanketing a beach.

2. When there is an offshore breeze, destroyers used as inshore supporting vessels may screen the approach of the boats into the firing position of the destroyers without blanketing their own observation and possibly that of offshore supporting ships, as indicated in figure 6. the tactical disadvantages of laying smoke under these conditions, however, are emphasized in many respects. The difficulties imposed on observation, signaling, fire from boats and ships, and control and navigation of boats, while the defender remains in a clear atmosphere, should be realized.

Figure 6.--Inshore supporting vessels screening boat movements.

3. 1. The orientation of smoke from a destroyer may be roughly computed as indicated in the following example: Suppose a destroyer is cruising at 25 knots from S to R (fig. 7); the wind is blowing from O to P at 5 knots. What will be the orientation of the smoke?

   2. As the destroyer is moving five times as fast as the smoke, lay off A-B five times A-C and draw the parallelogram A-B-D-C. When the destroyer is at B, the smoke will lie along B-C-E. When the destroyer as at R, the smoke will lie along R-F, parallel to B-C-E. If the destroyer is moving from R to S, the smoke will lie along lines parallel to A-D.

Figure 7.--Drift of smoke.

4. 1. The course of a destroyer to lay a cloud in a given position may be determined as indicated in figure 8.

   2. Chart the desired position of the cloud A-B; chart the direction of the wind C-D. Determine the speed of the wind, say 10 knots. Fix speed of destroyer, say 20 knots. From any point as E, on CD, lay off E-F twice E-B. From A, draw A-G parallel to F-E. Then, a destroyer steaming from G to A will lay the desired cloud along A-B.
   
   Figure 8.--Course of destroyers.

5. Destroyers can be used to advantage in connection with demonstrations, particularly at night, by laying smoke over extended areas and thus creating the impression of a large force.
837. Smoke from projectiles.--

     1. Due to the relatively large number of projectiles required to maintain an effective screen and the limited amount of stowage space available aboard ship, the use of smoke projectiles from ship's guns for screening and blanketing purposes will be exceptional. Projectiles loaded with white phosphorous may be used for producing casualties in personnel and as an incendiary, as well as for screening. The normal smoke, dust, and debris thrown up by any bombardment will often have a considerable blanketing effect.

     2. Smoke shell may be fired from mortars mounted in boats, but smoke should not be employed in this way at the sacrifice of an adequate density of high-explosive shell.

838. Smoke from boats.--

     1. Small boats, equipped with smoke tanks or candles, may be used to screen the movement of boats in a manner somewhat similar to that explained for destroyers. Fast boats should be utilized so that they may keep ahead of the leading wave while running a zigzag course. In employing burning substances, adequate safeguards must be taken against fire.

     2. Boats may also be used to drop smoke bombs or floats. Under favorable weather conditions, floats may be laid at a distance beyond shore machine gun range to cover the approach of boats laying such smoke floats closer inshore, thus continuously screening boat and aircraft operations from observation from low-lying ground positions ashore.

839. Illustrations; smoke laying by planes.--

     1. Aircraft smoke screen tanks.--The following illustrations have been selected for the purpose of demonstrating the maximum number of points in regard to the laying of smoke with aircraft smoke screen tanks rather than for the perfection of the execution.

        A battalion of marines is to land at H-hour, between points A and B on a frontage of 700 yards. A is approximately north of B. The problem presented aviation was to screen the movement of the boats and the landing of the troops, particularly from machine guns supposed to be located in the vicinity of points A and B. This picture shows a plane beginning to lay the first smoke screen at H minus 3 minutes, 400 yards from the beach. The plane laying the smoke is extremely vulnerable to fire from the beach, and its operations should be covered by other planes strafing and bombing the defensive positions. The boats, making 6 knots are 700 yards east of the beach. The pictures which follow were taken at intervals of approximately 30 seconds.

Figure 9.--Smoke screens.

Time H minus 2¹/2 minutes. This picture shows the development of the first screen. When the plane took off, the wind was southeast, but, before the screen was laid, shifted to the northeast. The pilot saw that the screen was laid too far to the south and is going back to try to fill in the northern part, but did not, however, have sufficient smoke left. This shows the necessity of having reserve planes or tanks available to supplement screens which are not effective. It may be noted that the plane would have been safer from enemy fire if it had returned outboard of the smoke.

Figure 10.--Smoke screens.

Time: H minus 2 minutes. Boats of the first wave can be seen approaching the smoke screen. The wind held fairly steady at from 3 to 5 knots. The smoke drifted to the southwest instead of the northwest, as expected by the pilot. This shows the necessity of determining the direction and velocity of the true wind shortly before a screen is laid. This may be accomplished by use of the drift sight on shore objects or smoke bombs. Observation of whitecaps or wind streaks on the surface of the water will permit a rough estimate of the direction of the wind.

Figure 11.--Smoke screens.

Time: H minus 1¹/2 minutes. The boats on the right are under direct aimed fire from the northern point, showing the necessity of having sufficient smokers to extend the screens well beyond the flank boats. When a battalion is landing on a separate beach, it is advisable to have the screen cover from two to three times the front of the battalion. This picture shows how a guide plane can see over the smoke and guide the boats to the proper landing. In the picture, boats are executing a change of direction to the right on signal from the guide plane.

Figure 12.--Smoke screens.

Time: H minus 1 minute. The second plane lays its screen 75 yards off the beach. Smoke is more effective when actually covering the defender, but this procedure requires more smokers; for example, if the second plane had laid its screen directly along the beach, the smoke would have drifted inland prior to the landing of the troops, requiring another screen at about H minus one-half minute. Boats are in the first screen and are well protected from observation and aimed flanking fire from the dock, indicating that this screen was laid the proper distance to seaward.

Figure 13.--Smoke screens.

Time: H minus one-half minute. The pilot of the second plane observed the drift of the smoke and laid his screen in the correct lateral position. The leading boats are in the smoke and are well covered from observation and aimed fire from the dock and point, and from the beach in between. Note the spread of the first screen compared to the second.

Figure 14.--Smoke screens.

Time: H-hour. The disembarkation from the boats is taking place in the smoke, indicating that, under existing weather conditions, the second screen was laid at the proper distance off the beach. The smoke is in the ideal location, that is, blanketing the defender during the most critical stage of the attack. Actually none of the troops were seen by observers on the beach while disembarking, and assaulting infantry passed within a few feet of these observers without being seen.

Figure 15.--Smoke screens.

2. Aero smoke bombs.--Figure 16 shows a smoke screen produced by smoke bombs dropped in the water by aircraft. As shown at right of the photograph, screens from smoke bombs are more effective when the wind is diagonal or parallel to the beach, the bombs being dropped upwind. Smoke bombs have certain advantages over smoke screen tanks. The bombs can be dropped from a considerable height, rendering the plane less vulnerable to enemy fire and not necessitating naval gunfire to cease; and the cloud is generated gradually on the surface of the water or land, consequently it can be maintained on the desired position for a longer period of time regardless of wind direction.

Figure 16.--Smoke screens.

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