US AAC/AAF Doctrine: FM 1-10, Air Attack, 1940 - 3. Tactics of Air Attack

CHAPTER 3: TACTICS OF AIR ATTACK

SECTION I - ADVANCE AND RETURN

83. GENERAL.-a. A bombardment mission normally consists of three separate phases - the advance, the assault, and the return. The advance phase ends when the attacking force is assembled in the air at the initial point, where the assault phase begins. The return phase begins at the rally point and ends with the return of the aircraft to their respective airdromes. (An initial point is a position in space at which the component units of a formation take up the disposition required for the execution of the assigned assault task.)

b. Secrecy and security are of paramount importance during the advance and return phases when the tactics are essentially defensive, as distinguished from the offensive tactics requisite to success in the assault phase. Security is important at all times during the mission, and secrecy is especially important during the advance, when it is desirable to avoid detection by the enemy and possible attack by hostile aircraft. Surprise is an important factor in the success of air attacks, particularly when directed against fleeting objectives.

c. It is desirable that the advance and return phases are as brief as possible, consistent with the requisite security measues. However, the routes followed during both the advance and the return may have to be circuitous in order to avoid passing over or near the stations of active elements of the hostile antiaircraft defense. During the advance, it is particularly important to avoid, when practicable, known or probable locations of observation stations pertaining to the enemy's aircraft warning service. As a matter of policy, bombardment units also avoid flight over areas defended by friendly antiaircraft artillery, but utilize to the maximum the protection afforded by friendly fighters in general or local defense.

84. UNOPPOSED OPERATIONS.-a. Situations in which the enemy offers no active resistance allow the most effective and economical employment of the bombardment force. Bombardment attacks, when made at night or during periods of very poor visibility, may be unopposed during the advance and return phases of the operation.

b. When the attacking force is not likely to encounter any active opposition, air attacks by individual airplanes afford greater ability to overcome adverse weather conditions; have greater effective ranges, greater maneuverability, and speed; are simple and permit maximum freedom in the exercise of individual initiative in coping with unforeseen difficulties. Individual airplane attacks may be employed to advantage in either day or night operations against undefended objectives, except when formation pattern bombing is required. Airplanes operating singly are able to attain maximum accuracy of offensive fire, thereby affording the most effective results from the munitions expended.

c. Even though active opposition may not be expected, the tactics of the advance and return should be such as to keep the force prepared to employ its defensive fire power quickly, and to guard against surprise.

85. PENETRATION OF ANTIAIRCRAFT DEFENSES.-Air attack operations are conducted against objectives which are vital to the enemy. The enemy will dispose the active elements of his antiaircraft defense forces in the manner best suited to the defense of those installations or facilities which are most vital to his military operations and which are vulnerable to air attack. On any specific mission against a vital objective, the penetration of hostile antiaircraft defenses may be necessary. Hostile antiaircraft defenses may be encountered at other points as well as in the vicinity of the objective. Knowledge of the nature, location, and strength of the defending forces, also of the probable weather conditions and the manner in which such conditions may affect both attacking and defending forces, is essential to the penetration of hostile antiaircraft defenses with a minimum of losses. The bombardment force may resort to evasion; may employ massed defensive fire; may be supported by light bombardment and/or fighter aviation; and also may take advantage of the security afforded by concurrent air operations.

86. EVASION.-a. The power of evasion is an important factor in avoiding contact with active elements of the hostile anti-aircraft defense forces. Routes and the time of the operation are selected with a view to avoiding detection. Areas in which enemy defensive aviation is active, also localities defended by antiaircraft artillery, and places at which there may be ground observation stations are avoided during the advance and the return.

b. Darkness, cloud formations, poor visibility, circuitous routes, speed, altitude, changes of altitude, camouflage, and inaudibility resultant from use of glides are factors which may be utilized to advantage to evade the hostile antiaircraft defense forces. Flight at high altitudes may be effective in evading detection by ground observation stations. Operations at minimum altitudes over uneven terrain may effectively mask antiaircraft artillery weapons. Reduced audibility in flight materially assists in obtaining surprise, either by preventing or by delaying discovery.

87. MASSED DEFENSIVE FIRE.-Tactical formations which facilitate the massing of the defensive fire of the bombardment command are used when contact with enemy fighter aviation cannot be avoided. In penetrating the air element of the hostile antiaircraft defense, the elements of the combat command are so disposed as to facilitate the rapid massing of its defensive fire power when within the zone of action of the hostile air fighting force.

88. SPEED AND MANEUVERS.-a. High speed and maneuver are employed to lessen the effectiveness of the fire of anti-aircraft guns. These methods are most effective at high altitudes when the time of flight of the projectile necessitates the use of firing data based upon a predicted position considerably in advance of the actual position of the aircraft when the gun is fired.

b. Single airplanes when not engaged in the actual bomb sighting operation resort to high speed and maneuver when taken under fire by antiaircraft guns. They change their altitude and their direction in such a manner as to make prediction difficult. Changes should be made at intervals shorter than the time of flight of the projectile, whenever practicable.

c. When taken under fire by antiaircraft guns, formations assume a spacing between airplanes greater than the effective zone of one antiaircraft artillery battery round and sufficient to permit maneuver of individual airplanes in the formation. When there are more airplanes than artillery directors, a portion of the airplanes may be able to complete the attack without receiving enemy fire. During daylight hours a formation spaced as stated above provides greater security than does a succession of individual airplanes. This is because the command is exposed to the antiaircraft gun fire for a shorter period of time.

89. LIGHT BOMBARDMENT AND FIGHTER SUPPORT.--Friendly light bombardment and fighter aviation may be employed in direct support of the attacking force in situations and phases which render such action practicable. Such support usually must be provided for in the plans of the next higher commander. Interceptor and support force fighter aviation and light bombardment aircraft, because of their limited radius of action, are not ordinarily employed in the direct support of long-range bombardment missions. Escort fighter aviation having long-range aircraft normally will be utilized if available when the direct support of bombardment units is required. Fighter support is especially important when strong opposition has to be overcome and the defensive fire power of the bombardment force is inadequate.

90. INDIRECT SUPPORT.-Bombardment operations may be afforded indirect support by concurrent attacks which may draw hostile fighter aviation to other areas. It is important that information of all contemplated air activities in the theater of operations be available, in order that bombardment operations may be so timed as to take advantage of the indirect support afforded by concurrent operations which may attract a portion of the hostile air fighting force.

91. SEARCH OPERATIONS.-When the accomplishment of air attack involves search operations for the purpose of locating the objective before launching the attack, the search constitutes a part of the advance phase of the operation. The tactics employed during search operations are based upon the active opposition likely to be encountered. Search operations may be conducted over sea areas, where active opposition by carrier-based aviation is to be expected. The technique of search is outlined in FM 1-20.

SECTION II - ASSAULT

92. ASSAULT DOCTRINE.-a. The assault phase of bombardment operations begins at the initial point and ends with the rally of the command for the return flight. The initial point is selected with a view to facilitating the effective conduct of the assault. The initial point always should be beyond the range of the antiaircraft guns employed to defend the objective and, if feasible, beyond the probable audibility range of the antiaircraft artillery intelligence service observers.

b. The security of the attacking aircraft always influences the tactics of the assault. The successful accomplishment of the mission is of paramount importance during the assault phase; but whenever, in the planning of the assault phase, there is conflict between security measures and maximum offensive effort, the commander must make a tactical decision with both considerations in view.

c. When the required degree of destruction of the bombardment objective can be accomplished at one blow, the bombardment force dispatched on the mission should be of sufficient size to accomplish the mission in one assault, thereby minimizing the time during which the bombardment command is exposed to enemy fire.

d. When the accomplishment of the mission requires more than one blow, the successive assaults should be so timed that the enemy cannot employ all of his defending fighters to oppose each attacking wave in turn.

93. ENEMY OPPOSITION.-Important objectives which are vital to the enemy may be strongly defended both by fighting aircraft and by antiaircraft artillery. Barrage balloons may be encountered in the vicinity of important objectives. When balloons are encountered, preliminary operations by supporting aviation may be necessary to destroy the obstructions before undertaking the air attack of the ground objective. The enemy may not be able to provide local antiaircraft defense for all objects which may constitute profitable targets for the attacking force; hence, the assault phase may be unopposed. Unless it is known that no opposition will be met in the vicinity of the objective, the operations plan should include provisions for appropriate action should opposition be encountered.

94. ASSAULT VARIATIONS.-a. Bombardment forces exert their power by air attack operations. Assaults may be delivered at high or low altitudes, during daylight or at night by means of area or precision bombing; and may be opposed or unopposed by the enemy. It is, therefore, manifestly impossible to lay down any system of set rules to be implicitly followed in all situations.

b. For convenience of presentation, tactics of the assault are treated in this chapter under the categories of high altitude and minimum altitude operations. High and minimum altitude operations are distinguished not so much by the actual height at which the assault is made as by the difference in the character of the operation, particularly with reference to delivery of fire and by the manner of effecting surprise and of obtaining security against the fire of hostile weapons wherever located. Operations which normally are conducted at altitudes of 5,000 feet or more above the ground may, by reason of weather condition or other factors, actually be performed at a comparatively short distance above the ground (1,000 to 3,000 feet in some cases) ; however, the operation is tactically a high altitude operation though the actual altitude may be relatively low. Altitude, considered as a separate factor, affords security at both extremely high and at extremely low levels. Only those missions which usually are performed at minimum altitudes, or which employ forward protective fire as a security measure, are treated as minimum altitude operations.

SECTION III - HIGH ALTITUDE BOMBING

95. GENERAL.-a. (1) Bombing attacks involving the performance of precise sighting operations are treated herein as high altitude bombing. Such operations may be conducted within one or more of the following altitude brackets:

(2) From an offensive point of view the best altitude from which to launch an attack is the one which is most favorable to the obtaining of the greatest accuracy of offensive fire. The altitude may be modified by considerations of security or weather. High altitude bombing operations may be conducted either by day or at night, the decision being influenced primarily by the effectiveness of enemy opposition. Undefended objectives can be most effectively attacked during daylight. Strong enemy opposition may necessitate night operations against important objectives in order to minimize losses.

b. When air attacks are made against objectives having an organized antiaircraft artillery defense, the proper force should be employed to accomplish the purpose of the air offensive in one mission, if this force is available. In conducting the attack, security is gained by attacking simultaneously with as many aircraft as can conveniently and expeditiously do so. Where conditions indicate the necessity for attack by waves, the time interval between waves should be reduced to a minimum. The time of passage of each wave through the defended zone is also held to a minimum.

96. DIRECTION OF APPROACH.-a. The nature of the target should be carefully considered. Objectives which are compact and approximately square or circular in shape may be attacked equally well from any direction. Elongated targets may be attacked either across or along their long axis when range and deflection probable errors are equal and bombs are individually sighted. When range and deflection probable errors are not equal, the direction of approach for independently sighted bombs, other conditions being favorable, should be such that the greatest probable error is in the direction of the long axis of the target. An elongated maneuvering target may have to be attacked as found, regardless of the direction of approach with respect to the axis of the objective.

b. Visibility is an important factor in precision bombing. The direction of approach should afford best visibility for the bombing teams and poorest for opposing antiaircraft forces. Approaching from the direction of bright sunlight, moonlight, or protecting clouds may provide definite advantages to the attacker.

c. Upwind approaches are most favorable for bombing accuracy because of the lower ground speed, but the bomb release point is thereby brought closer to the target and the exposure of the aircraft to antiaircraft artillery fire some-what prolonged. Antiaircraft artillery fire usually is more accurate against slow than fast moving aircraft. The advantages of reducing exposure to antiaircraft gunfire must be considered in comparison with the decrease in bombing accuracy resulting from the greater ground speed incident to a downwind approach.

97. ALTITUDE.-Altitude affects the accuracy of precision bombing. In general, bombing accuracy is best at relatively low altitudes but the loss in accuracy is not necessarily directly proportional to the altitude. The altitude at which best accuracy has been attained by individual teams or bombardment units should be used whenever practicable. Bombing teams should be trained to do accurate work at the lowest altitude at which they may be forced to bomb because of ceiling limitations imposed by clouds. The accuracy of antiaircraft artillery fire varies with the altitude of the aircraft fired upon and is, in general, best at medium altitudes and poorest at fairly low or extremely high altitudes. The optimum bombing altitude in any situation can be ascertained only after careful consideration of bombing accuracy as against antiaircraft fire effectiveness and the consequent probable losses of aircraft.

98. SIGHTING OPERATION IN FORMATION BOMBING.-a. Formation bombing has the disadvantage of sacrificing to some extent the accuracy obtainable in separately sighted single releases. The formation leader is responsible for directional accuracy, and the bombing team of the leading airplane should exercise extreme care to minimize the directional error. The deflection errors of bombs dropped from other aircraft in the formation are affected by the precision with which these aircraft are controlled in maintaining their position in the formation. Bomb sight controlled timing of the release of the bombs dropped from each airplane in the formation is essential to the minimizing of range errors and to assuring compactness of the pattern.

b. Release upon signal or when the bombs are seen to leave the leading airplane involves an uncontrolled delay which may result in large range errors at high ground speeds and also subjects all bombs to any initial range error made by the leading bombardier. Each airplane in a bombing formation must have a trained bombing team. Since it cannot be foreseen what aircraft may become casualties, the success of the mission must not be jeopardized by placing full responsibility for the entire sighting operation upon the bombing team of the leading airplane. It is necessary that every bombardier and every bombing team be fully trained in the performance of the complete sighting operation and capable of taking the lead whenever the need for such action arises.

99. DAYLIGHT OPERATIONS.-Good visibility is an important factor in securing the most effective results in high altitude bombing attacks. Such operations normally are conducted during daylight unless other factors render night operations more desirable or necessary. All kinds and classes of objectives can be effectively attacked during daylight. The methods employed in the attack of area targets in daylight frequently differ from those best suited to the attack of point targets.

100. DAYLIGHT ATTACK OF AREA TARGETS.-a. Area bombing is employed against targets which cover a considerable space with no single vulnerable point, the destruction of which insures the destruction of the objective. Area bombing is also employed when the general location of the objectives is known but their exact placement cannot be determined with sufficient accuracy to permit them to be used as aiming points. Precision sighting is necessary in bombing an area in order to insure the correct placement of the bomb pattern. Area bombing against defended objectives normally is conducted in formation. When the size and shape of the target area are such that the conformation of a single formation can be adjusted to produce a bomb pattern covering the entire area, all of the attacking aircraft may operate in a single formation as one combat command.

b. The attack of an extensive area requiring a large attacking force may be accomplished by dividing the force into suitable separate combat commands and assigning each attacking unit a definite subarea against which it is to operate. If the objective is defended, all units of the attacking force should assault it as nearly simultaneously as possible. The direction of approach should be such as to minimize the number of guns which can be brought to bear upon the attacking force, and also to make the exposure to antiaircraft gunfire as brief as possible. In the attack of area targets, bombs usually are released in train.

101. DAYLIGHT ATTACK ON POINT TARGETS.-a. Objectives consisting of point targets requiring the accurate placement of bombs, individually or in a closely spaced train, are attacked by precision bombing methods. Point targets may, depending upon their size and nature of construction, be attacked by aircraft operating either singly or in formation. When formation attacks are made against point targets, the assault formation usually must be compact in order to secure a suitably concentrated bomb pattern. When the target is undefended, the assault tactics are based solely upon the requirements for the most effective employment of the attacking force. Individual airplane attacks are the most effective against undefended point targets because the attack can be repeated by dropping bombs singly until the desired result is attained. Avoidance of contact with active elements of the hostile antiaircraft defense force may be practicable during the advance and up to initiation of the bombing approach by employing evasion tactics, but evasive maneuvering is not feasible during the bombing approach. (Bombing approach is the brief period of flight of the bombing airplane or formation during the actual sighting operation and immediately preceding bomb release.)

b. Effective results are of paramount importance. However, when the target is defended, the assault tactics may, within limits prescribed by higher authority, be modified so as to minimize the effectiveness of the enemy's opposition. High altitude daylight bombing attacks in the presence of defending antiaircraft artillery, aircraft opposition being either weak or absent, may be effected by simultaneous convergence upon the target, either by individual airplanes or by flights, thus permitting individual sighting for release of each bomb or train of bombs. When the simultaneous convergence method of attack (either by individual airplanes or by flights) is employed, it is desirable that the initial point be as close to the objective as practicable without being within the horizontal range of the defending antiaircraft artillery. When the attacking aircraft are exposed to antiaircraft gun-fire for a considerable period, they should maneuver individually when not in the bombing approach in order to lessen the effectiveness of the fire.

102. NIGHT OPERATIONS.-a. (1) High altitude bombing operations can be conducted at night whenever the conditions are such that the target can be seen and the necessary sighting operations performed. Artificial illumination of the target frequently is necessary at night. Initial illumination usually is provided by observation or reconnaissance aircraft as an auxiliary supporting operation. Darkness imposes limitations upon both the attacking force and hostile antiaircraft defense forces because of the decreased visibility. Direct illumination of the attacking aircraft normally is required for the proper direction of the fire of antiaircraft guns. Aircraft when directly illuminated and not in their bombing approaches may resort to high speed and to changes in altitude and direction in order to lessen the effectiveness of the antiaircraft artillery fire. Under favorable conditions, search-lights provide a considerable amount of general illumination by reason of diffused rays not forming an integral part of the focused beam.

(2) Aircraft flying at high altitude cannot be seen from the ground unless directly illuminated. However, nearby aircraft not in the beam of a searchlight are sufficiently illuminated to make them visible to other aircraft which are only a short distance away. Hostile fighting aircraft can take advantage of the illumination provided by searchlights and can, by proper maneuver, fire upon the attacking force without themselves being illuminated long enough to enable the defending gunners to retaliate upon equal terms. However, fighter air-craft cannot effectively attack unless their targets are within the limits of an illuminating beam.

(3) High altitude night attacks, whether against defended or undefended objectives, normally are accomplished by individual airplane attacks. Attacking aircraft by approaching the objective at night in a glide from high altitude may be able to introduce an element of surprise and thereby delay detection and minimize the time of exposure to hostile anti-aircraft fire. In some situations, it may be possible to employ gliding during both the approach and the retirement. b. (1) Area targets which are of practically uniform vulnerability throughout can be attacked at night from high altitude when the illumination is sufficient to facilitate definite identification of the area, even though details within the area may not be distinguishable. When the size and shape of the area to be attacked are such that full coverage can be obtained by a formation bombing pattern, attack in formation is effective and expedites completion of the mission, but for defensive reasons is normally inadvisable against defended targets. Individual bombing is relatively more accurate and should be employed when feasible.

(2) During night attacks by individual airplanes, bombs may be released in salvo, in train, or singly, depending upon the requirements of the situation. Undefended targets are attacked in the manner best suited to the accomplishment of the desired results and with the minimum expenditure of bombs. Individual airplane attacks normally are employed in high altitude night operations against point or area targets.

103. ILLUMINATION OF TARGETS.-A plan of illumination should provide that

a. The entire coordination and/or success of the maneuver should not depend upon the performance of any individual airplane or flight, or upon a complex scheme of coordination between flight units.

b. The objective should be illuminated before the assault aircraft are so committed to their attack as to be beyond the control of unit commanders. This may, in some cases, involve illumination of the objective prior to departure of the assault units from their initial points, notification of the discovery of the target being furnished the assault units by pyrotechnic and/or radio signal.

c. Illumination should be maintained until the attack is completed.

104. FLIGHT METHOD.-a. This method of attack can be employed by any size of bombardment force from a single flight up to and including a group. It is essentially a night method of attack but can be used in daylight in the absence of pursuit opposition or with the protection of friendly pursuit. It is illustrated in figure 8. ( Figure in the Appendix)

b. (1) In this method the assault unit is led to an initial point beyond the range of defending antiaircraft artillery and the range of its sound locators, provided the hostile anti-aircraft intelligence service is localized to a matter of 20 to 25 miles around the objective. At the initial point the assault unit circles, and flights of three aircraft detach themselves successively and advance in the assault. The interval between assaulting aircraft is normally prescribed in orders. The customary interval is 10 seconds, but variation from this amount may be necessary to meet local requirements.

(2) An alternate method to achieve the flight spacing may be employed. In this method, flights take the prescribed interval during the advance shortly before arrival at the initial point. They, therefore, arrive at the initial point at the proper interval for the initiation of their assaults, thus eliminating necessity for circling at the initial point.

c. (1) The altitudes of attack and withdrawal are pre-scribed in orders for each airplane of all flights. The flight normally departs from the initial point at the assault elevation of the leading airplane. The leading airplane of the flight proceeds directly toward the objective at its attacking altitude; the numbers two and three airplanes swing to the right and left, respectively, executing shallow dives to their prescribed assault altitudes which usually are 2,000 and 4,000 feet respectively, below that of the leading airplane. At the proper time the numbers two and three airplanes change their course so as to converge upon the objective within an arc of from 30° to 50°. The points at which the numbers two and three airplanes change course to converge upon the objective may be determined by an estimated time of arrival, or may be prominent landmarks readily distinguished at night where such landmarks are conveniently available.

(2) Immediately after releasing their bombs the assaulting aircraft turn approximately 180° and withdraw at a pre-scribed altitude, usually 1,000 feet lower than its assault altitude. This withdrawal is made approximately on the line of the advance. The number two airplane normally turns to right and numbers one and three to the left. Altitudes are prescribed so as to avoid interference and to confuse the defending artillery directors; for example, the leading airplane may attack at 12,000 feet and withdraw at 11,000 feet; number two attacking at 10,000 feet and withdrawing at 9,000 feet; and number three attacking at 8,000 feet and withdrawing at 7,000 feet. During daylight the altitude intervals may be smaller than are required for safety in night attacks. The assault procedure is repeated by each successive assaulting flight.

d. This method of attack renders difficult the detection and illumination of individual aircraft. When 10-second intervals are used, the number of aircraft within range of the anti-aircraft artillery usually will exceed the number of firing batteries. By this method the bombardier of each airplane performs an independent sighting operation.

105. SQUADRON METHOD.-a. (1) The squadron method of attack is designed primarily for use at night but may be employed in daytime in the absence of effective pursuit opposition, and when weather or cloud conditions favor it. In this method of attack each squadron is assigned a separate initial point to which it proceeds from the group initial point. The squadron aircraft proceed individually to assault their objectives at the altitude and intervals prescribed in group orders.

(2) The interval between successive squadron aircraft is usually 10 seconds but may be greater for special situations. The assault technique is similar to that employed in the flight method. Airplanes, one from each squadron, attack simultaneously and then return to their respective squadron initial point. Restricting the sector of advance for a four squadron group to 45° favors the creation of a confusion of sound.

b. Circling the initial point prolongs the time of the bombardment force over enemy territory, and care must be exercised to prevent circling formations from being illuminated and fired upon by surprise. The squadron method of attack is illustrated in figure 9. ( Figure in the Appendix)

106. BASE ALTITUDE METHOD.-a. In the base altitude method one initial point is used and the squadrons of the group arrive there at successively at 1 to 2 minute intervals. The order for the attack specifies a base altitude, which is the lowest altitude from which bombs are released during the mission. Each squadron upon arrival at the initial point, separates into assault units which may be either individual airplanes or flights. The leading assault unit dives and proceeds directly toward the objective and bombs from the base altitude. The other units form an echelon, each to the right of its immediate predecessor, and bomb successively from a slightly different direction and at successively higher altitude intervals of 500 feet.

b. When a base altitude of 10,000 feet is prescribed, the leading assault unit bombs at that altitude, the second unit at 10,500 feet, the third unit at 11,000 feet, and so on. Each squadron arrives at the initial point at or above the highest altitude from which it will release bombs. This method provides for release of bombs singly, in salvo, or in train by separate sighting operations in each airplane and is suited to daylight attacks against objectives defended by antiaircraft artillery. Some coordination of defensive fire against hostile pursuit is obtained when the assault unit consists of a flight.

107. GLIDE METHOD.-The various methods of attack may be modified so that assault units approach the bomb release line in a glide instead of in horizontal or diving flight. A glide approach reduces the sound made by the aircraft, thereby lessening the likelihood of discovery particularly at night, and also introduces a range change factor which may adversely affect the accuracy of the antiaircraft artillery fire.

SECTION IV - MINIMUM ALTITUDE BOMBING

108. GENERAL.-a. The advance and return phases of minimum altitude air attack operations usually are flown at altitudes which facilitate accurate navigation and afford a considerable degree of security from the fire of ground machine guns and of antiaircraft guns. Assaults which bring the attacking aircraft within range of machine guns, small cannon, and small arms on the ground should be performed at an altitude which is a compromise between the desire for most effective offensive fire and security from ground weapons. Practically any type of small bore light weapon may be used in defense of an objective against low altitude air attacks, and for that reason there always is likelihood of encountering hostile fire during such operations.

b. Minimum altitude assaults may be delivered either in daylight or during the hours of darkness. The attack of objectives which are undefended or only lightly defended can best be accomplished during daylight. When strong opposition is anticipated, it is desirable to take advantage of the security afforded by darkness.

c. When minimum altitude attacks are performed in support of high altitude operations, proper coordination is essential to the maximum effectiveness of the combined operation. Coordination in supporting air attacks normally is effected by adherence to a time schedule, rather than by assembly with the force which attacks at high altitude.

109. DAYLIGHT OPERATIONS.-a. Minimum altitude bombing operations normally are conducted during daylight unless night operations are required. During daylight the aircraft engaged in minimum altitude attacks usually operate in formation. They may operate singly for short periods in the vicinity of the objective when the mission requires or permits individual airplane attacks. Aircraft employed in minimum altitude assaults during daylight habitually employ forward protective fire while within range of ground weapons of the forces defending the objective. Operation at minimum altitude, particularly over irregular terrain, affords security to the attacking force because of the masking of the fire of ground weapons and by limiting the time of exposure to any particular weapon. Defensive formations are employed for protection against hostile fighting aircraft which, because of the low altitude, can attack only from the upper hemisphere.

b. Surprise is sought whenever possible. It is gained by taking advantage of speed and of the defilade provided at minimum altitudes by irregular terrain. The operations of two or more attacking units assaulting the same objective are so coordinated as to secure the maximum possible surprise.'

c. When the objective is strongly defended, the attack is accomplished by a single assault in suitable offensive formation. In such cases, the main attack may, when practicable, be preceded by a preliminary operation for the purpose of laying smoke to interfere with the hostile antiaircraft defense force and to afford cover for the main attacking force.

110. AREA TARGETS.-Minimum altitude daylight attacks against area targets normally are accomplished in formation. The whole attacking force may assault the objective in a single formation or, when such a maneuver is not suited to the particular situation, the attacking force may be divided into small units, each of which is assigned a specific portion of the area against which to operate. In covering large areas, general destruction and demoralization are of greater importance than accurate fire against particular points within the area. The direction of approach is selected with due consideration of the concealment afforded by irregularities in the terrain, position of the sun, nature of the target, and enemy defensive measures. The direction and velocity of the wind are important factors affecting the utilization of chemical agents in connection with the assault.

111. LINEAR TARGETS.-Linear targets, such as marching columns and motor or railway trains, are attacked either by individual airplanes or small formations in column, formations being used when the width of a single airplane attack is insufficient to attain the desired result. The attacking units approach obliquely, turn, and fly over the objective only during the actual delivery of offensive fire.

112. POINT TARGETS.-The type of sighting equipment and nature of fire used usually determine the minimum altitude at which precision bombing can be accomplished. Minimum altitude attacks against point targets are effected by individual airplanes, unless the size and nature of the target are such as to require the employment of a formation attack. When a number of separate point targets are located within a relatively limited area, the attacking force may fly in formation to the critical area. The individual aircraft then operate singly only during the short interval required for assaulting their respective assigned targets. Smoke may be employed in conjunction with the attack of point targets during day-light, but care must be exercised in order not to obscure the targets themselves in such a manner as to interfere with the effectiveness of the attack.

113. NIGHT OPERATIONS.-a. Darkness definitely limits the effectiveness with which low altitude attacks can be accomplished but at the same time interferes with the employment of the active elements of the hostile antiaircraft defense forces. Night attacks at minimum altitude are effected by airplanes operating singly, unless the size and nature of the target are such that formation attacks are required in order to attain the desired results.

b. Enemy activities conducted at night to utilize the security normally afforded by darkness may result in many targets suitable for minimum altitude air attacks being available only during the hours of darkness. Night attacks are resorted to when time is pressing, when effective results can be obtained against objectives not available during daylight, or when the defenses are so strong as to prohibit the assault being launched during daylight without incurring excessive losses.

c. Assaults launched at dawn enable the attacking force to utilize the security afforded by darkness during the advance phase of the operation and may gain a considerable element of surprise. Opportunities for the effective launching of minimum altitude attacks at dusk may occur when enemy preparation for night movement is in process. Darkness is utilized for the return phase of the operation after an assault at dusk. This may prevent hostile aircraft from tracking the attacking force to its airdromes. Darkness is the principal security factor for aircraft engaged in minimum altitude assaults at night.

114. ILLUMINATION OF TARGETS.-Since it is essential that the attacking force be able to see the target, artificial illumination frequently is required during night operations. At night, initial illumination of the target may be provided by observation or reconnaissance units operating in support of minimum altitude bombing. When successive assault waves are used at night, the successive individual airplane attacks' can be so timed that each airplane after completing its assault can climb to a suitable altitude and drop a flare to illuminate the target for the succeeding airplane.

115. COORDINATION OF NIGHT ATTACKS.-When an area target is attacked at night by means of coordinated assaults by two or more separate attacking forces operating at minimum altitude, each unit force is assigned a definite zone in which to operate. Coordination of the attack as a whole is obtained by having the unit forces operate in accordance with a time schedule. When minimum altitude assaults are launched at night in support of high altitude operations, coordination is obtained by means of a time schedule which must be accurately followed by both supported and supporting. forces in order to secure the most effective results.

116. NEUTRALIZATION OF ANTIAIRCRAFT ARTILLERY AT NIGHT.-Minimum altitude night attacks in support of high altitude operations normally are directed against the searchlights of the opposing antiaircraft artillery. In rendering such support it is necessary to destroy or neutralize only those searchlights which serve gun batteries so located as to be able to deliver effective fire into the sector of approach of the high altitude attacking force.