THE COMMANDER'S PLANS.—Once troops are committed to the assault the commander is powerless to divert them to another purpose. His control is exercised in {58} the correct interpretation or adaptation of his original plan by his subordinate commanders. Before launching his troops to the attack in accordance with the decisions arrived at from information received, the commander will assemble his subordinates and the representatives of co-operating arms or formations in order that his plans may be explained. This conference should be held at such a time as will enable his subordinates to explain their rôle to the sub-unit commanders. Wherever possible the conference should be preceded by a personal reconnaissance of the ground over which the attack is to be made, otherwise a map of the district concerned must be substituted for the actual view.
The commander will be influenced in his plans by the state of the campaign at the time of the decision to attack. In the opening stages of a campaign in a thickly populated country, and generally throughout a campaign in less settled districts, a war of manoeuvre will lead to the "Encounter Battle," and the objective to be aimed at will be limited only by the power of endurance of his troops, the weather conditions, and the possibility of supplying his victorious troops with ammunition and food. Under other conditions, the objective will be subject to further limitations, as the defensive position will be organised in great depth, and while effective penetration will thus be more difficult to achieve it must, of necessity, be accompanied by widening in proportion to its depth in order that space for manoeuvre and facility for communication may be secured. The Infantry Attack will be conducted on the same lines in both forms of battle, but the greater the organisation of the defensive position the more limited will be the depth to which the attack can be carried on and the greater difficulty will there be in launching reserves in pursuit.
THE POSITION OF ASSEMBLY.—A column in march formation will very rarely move to its attack position, or "jumping-off place," from column of route except {59} where there are concealed lines of approach to the spot. A Position of Assembly will therefore be assigned, and this will be chosen with a view to cover for the troops and facilities for the issue of food and hot drink, the distribution of ammunition and the filling of water bottles. As a general rule, it is left to the battalion commander to select Positions of Assembly for each of his companies. When large bodies of troops are assembled with a view to immediate action, it must always be remembered that large forces cannot be moved by a single road if all arms are to be brought into action at the right moment. In April, 1864, General Banks, with 25,000 U.S. troops, moved from Grand Ecore to Pleasant Hill in the Red River Valley. Although lateral roads existed, his column marched on one main road only, and twenty miles separated his front and rear. As he came into action with General Forrest, of the Confederate Army, the head of his column was defeated and thrown back again and again by forces inferior in total strength, but superior on the field of the encounter. Had General Banks used two or more parallel roads, which were available for his use, the Confederates on the spot would have been quickly overpowered.
THE ATTACKING FORCE.—The commander must decide against which portion or portions of the hostile position, or along which lines of advance, his Fire Attack shall be developed. As the object of this movement is to pin the enemy to his position, to wear down his resistance generally, and particularly at the point where the Decisive Attack is to be delivered, as well as to effect a lodgment in the position, it is clear that the greater the extent of the objective the better, and one or both flanks should be threatened if possible. But whenever a Fire Attack is developed it must be in sufficient strength to occupy the enemy's attention fully and it must be carried through with vigour once begun. One {60} to three rifles per yard of the objective to be assailed is generally regarded as the requisite strength of the Forward Body, Supports, and Local Reserves. At St. Privat (August 18, 1870) a first and second line made a frontal attack and came under fire of the French chassepots, to which their own shorter-ranged rifles could make no effective reply. The lines pressed on, but were ultimately brought to a standstill through lack of reinforcements, which could have been sent up against the flank of the fire position which was holding up the attack, under cover of the fire of the troops in position, and would thus have carried the Forward Body to the assault.
Equally unsuccessful was Osman Pasha's attempt to break through the investing lines at Plevna (December 10, 1877). With 15,000 troops he pierced the Russian lines, and another resolute effort would have carried the sortie through the investing forces. But the 15,000 Supports could not get out of the town as the bridges and gates were blocked with fugitives and wagons.
THE DECISIVE ATTACK.—The commander must also decide the point and direction of the Decisive Attack. This will be made on a part of the front or on a flank, and it may be predetermined in accordance with information concerning the hostile dispositions, or it may have to be ascertained by further fighting. The advantages of a Frontal Attack are that, if successful, the enemy's force is broken in two parts, the separated wings may be driven back in divergent directions and overwhelmed in detail, and a decisive victory is thus obtained. The disadvantages are that the force assaulting a part of the enemy's front draws upon itself the concentrated fire of the whole hostile line, and unless the Fire Attack can master this fire the decisive blow will be held up, while an unsuccessful frontal attack invites the enemy to advance and to envelop the assailants. The advantages of a Flank Attack are that {61} the enemy's line of retreat is threatened, and only the threatened flank can concentrate its fire on the assailant. The disadvantages of a Flank Attack are that the enveloping troops have to face a similar danger on their own outer flank, for upon this point the defender will almost certainly direct his counter-stroke, and for this reason a decisive blow on the enemy's flank must be followed up by strong reserves. The flank chosen for attack will be that which affords the best opportunities for converging fire from the supporting artillery, which gives the best line of advance for the infantry, and where success will have the most decisive results, the last depending mainly on the extent to which the enemy's line of retreat is threatened. Where the various requisites are in conflict, the flank affording the greatest advantages for converging fire from the artillery will be chosen. Nothing destroys the moral of men in action so speedily and effectually as a flank attack, and except by this method good infantry will seldom be beaten.
A decisive attack, to be completely successful, must be followed up by fresh troops before the assaulting waves have been checked. Lee had crossed the Potomac and desired "to defeat the last army of the Federals in the east and drive the Northern Government from Washington." The battle of Gettysburg lasted three days (July 1-3, 1863). On the first, the army of Northern Virginia was uniformly successful; on the second, the fortunes of battle swayed to and fro; on the third, Lee decided to make a Napoleonic decisive attack with half his available troops against Meade's centre. But the spirited attack of the first 15,000, after penetrating the line, was checked, and the remaining 15,000 did not arrive in support, so that the attack died down, was repulsed, and withdrew in disorder.
At Chattanooga (November 25, 1868) Grant's decisive attack was successful, although delivered against a part of the position which appeared to be impregnable, on account of the strength of the attack, through {62} distribution in depth; 25,000 men were hurled against the entrenchments in three lines, and the support of the third line carried the waves of the attack through the defences.
DETAILING THE UNITS.—The commander will detail the units for carrying out the Fire Attack, which will generally require one to three rifles per yard of the objective. This force will be placed under a definite commander, who will distribute it into a Forward Body to develop the attack in the firing line; Supports, to enable the Forward Body to assault the position; and Local Reserves to maintain or restore the advantages gained, their main function being to repel counter-attacks by similar bodies of the enemy and to maintain the offensive spirit.
The commander will also detail the units for carrying out the Decisive Attack, which will require three to five rifles per yard of the portion of the position against which it is projected. This force, under a definite commander, is distributed for the attack in depth, so that the strength and weight of the blow carries it home against all opposition. The force is retained by the commander of the whole attacking troops, to be thrown in at the right time and in the right place. It also remains in hand to restore the battle in case of an unexpected check, or to cover the withdrawal of the remainder of the troops if it is desired to break off the engagement.