Flank Attacks and Flank Guards
“A man thoroughly penetrated with the spirit of Napoleon’s warfare would hardly fail to make his enemy’s communications his first objective.”—-Col. G. F. R. HENDERSON.
The Flanks are the most vulnerable points of an army, for an attack upon these points subjects the defenders to enfilade fire, and is delivered by troops arrayed in attack formation against an enemy that is not in a position to repel the attack. The consequences of a successful Flank Attack are so far-reaching that every effort will be made by a commander to bring about such a consummation in order that he may sever his adversary’s communications, bring him to the end of his resources, and deprive him of the means of replenishing them.
If, therefore, there is any possibility of a column on the march being attacked in flank a force must be detached to protect that flank, and if both flanks are exposed to attack both must be similarly protected. The flank is the most vulnerable part of a moving column, and an attack driven home upon that part has every prospect of success, for it will be delivered by a force that is distributed in depth against a force that is protracted in width after changing front to meet the attack, and the absence of depth in the defending force will deprive the defence of the principal source of strength in resisting attack.
An independent column is liable to attack on either of its flanks, unless the nature of the country through which it is passing provides security for one or the other in the form of an impenetrable feature (such as a wide, trackless marsh), or an impassable barrier (such as a neutral frontier). The outer columns of a force moving on parallel routes will have an exposed flank, while their inner flank is protected by maintaining touch with the neighbouring column.
Flank Guards may be furnished by the Main Body, or by the Advanced Guard, and this point will be made clear in the orders for the operations. Their composition, strength, and distribution, and the interval at which they move on the flank of the Main Body, are similar to those of an Advanced Guard, while their action under all circumstances is governed by the same tactical considerations, the principle underlying every action of a Flank Guard commander being compliance with the known intentions of the commander of the Main Body, and the sacrifice of the interests of the Flank Guard to preserve the interests of the Main Body. The same duties of reconnaissance and protection have also to be carried out, and communication with the Main Body has to be maintained. For the purposes of reconnaissance and communication Aircraft are even more effective than in Advanced Guard work, while observation patrols supplement and confirm the reports of aërial observers. The work of protection varies with the nature of the country through which the Guard and the Main Body are moving at the particular time. In open country the Flank Guard may be keeping pace with the Main Body at a regularly maintained interval, and on parallel lines. In close country, and in hilly or mountainous districts, it may be necessary to occupy a successive series of tactical positions on the exposed flank, any of which can be reinforced and held at need to safeguard the passage of the Main Body. In order that the whole column may be protected, from the head of the Main Body to the train in rear, unbroken touch must be maintained both with the Advanced and the Rear Guard, and incursions between these forces and itself must be prevented by the Flank Guard.
In addition to the protection of a column on the march, Flank Guard work is of the highest importance on the Lines of Communications and in the protection of Convoys. On the Lines of Communications raids from the air or land may always be expected in Manoeuvre Warfare, and one flank is usually more vulnerable than the other. A Convoy, when parked, is liable to attack from any quarter; and when on the march it may be assailed from any direction, especially when the adversary can detach mounted troops, or infantry rendered mobile by motor transport, or raiding bodies carried in Aircraft. Frequently, however, one flank only of the Lines of Communications is vulnerable owing to the geographical or tactical situation, and the work of protecting traffic or Convoys on the Lines of Communications is Flank Guard work, with due precautions against surprise from all quarters, the Main Guard remaining with the Convoy and securing its safe arrival at its destination, rather than seeking an encounter with the enemy. The most efficient way to protect a Convoy is to piquet the road daily with troops sent out from posts on the line; but when it is necessary to send a Convoy by a route which cannot be protected in this way a special escort must be provided. The commander of an escort will not engage the enemy if his task can be accomplished without fighting. If fighting is inevitable the enemy should be engaged as far from the Convoy as possible, and it will not be halted and parked, except as a last resort. In the case of mechanical transport the whole of the escort will be carried in motor vehicles, and except where parallel roads are in existence, little can be done to secure flank protection while on the move. A portion of such escort will move with the Convoy and a portion will be sent ahead to secure any bridges or defiles which have to be passed, the outlet of any defile being secured before the Convoy is permitted to enter the defile. In the case of a horsed Convoy the escort will usually consist of infantry, with a proportion of mobile troops. Small Advanced and Rear Guards will be detailed and sufficient men will be posted along the column to ensure order and easy communication. The remainder of the escort will usually move on that flank from which attack is most likely.
The far-ranging raid on the Lines of Communications was a notable feature of the American Civil War. It was freely employed on both sides and was often harmful to the object of the attack and usually profitable to the raiders, especially to those of the South, by reason of the replenishment of stores. General Turner Ashby, the dashing cavalry leader in the Shenandoah Valley, was a constant source of terror to the Northern Generals, and his death while protecting the movements to Cross Keys (June 6, 1862) was a terrible blow to Stonewall Jackson, who employed his mounted troops with more skill than any other commander, Confederate or Federal. General R. E. Lee possessed a great cavalry leader in J. E. B. Stuart, “but cool-headed as he was, Lee appears to have been fascinated by the idea of throwing a great body of horsemen across his enemy’s communications, spreading terror among his supply trains, cutting his telegraphs and destroying his magazines. Yet in hardly a single instance did such expeditions inflict more than temporary discomfort on the enemy; and the Confederate Armies were led more than once into false manoeuvres for want of the information which only the cavalry could supply. Lee at Malvern Hill and Gettysburg, and, on the side of the North, Hooker at Chancellorsville, and Grant at Spottsylvania, owed defeat in great measure to the absence of their mounted troops on raiding excursions. In the Valley, on the contrary, success was made possible because Jackson kept his cavalry to its legitimate duty” (Henderson “Stonewall Jackson”). In the Russo-Japanese War a column of 500 Cossacks, under Colonel Madritov, made a bold raid on the communications of the Japanese I. Army in the last days of April, 1904. The raid involved a ride of 240 miles and was carried out in entire ignorance of the imminent attack upon General Zasulich’s force by the Japanese I. Army at the Battle of the Yalu (May 1, 1904). On arrival at his objective Colonel Madritov found nothing to attack, as the base of the Japanese I. Army had been shifted from the Korean frontier to a shorter sea base at the Yalu mouth. On his return he found his General in disordered flight, and had his small force been available at the Battle of the Yalu it could have protected the retreat to Hamatan and Feng-hwang-cheng. Raids and attacks outside the centre of operations, however daring, have no permanent value.
In the South African War a disaster to a Convoy at Sannah’s Post, or Koorn Spruit (March 31, 1900), was caused by the absence of precautions in front of a retreating force, the wagons being permitted to enter a defile (the Spruit crossed the road at right-angles and was held by the Boers) before the exit had been secured. Earlier in the same campaign a Convoy of 800 wagons was lost at Ramdam (February 13, 1900). An ambushed force of Boers killed all the transport animals and the wagons were abandoned. No escort had been provided for the Convoy, which entered the ambushed area without previous reconnaissance. Throughout the South African War the activities of De Wet emphasised the vulnerability of the Lines of Communications.
Where the tactical situation permits, arrangements should be made to protect the Lines of Communications by offensive action. An engagement may be invited in a suitable position, the protecting troops holding the raiders with a Delaying Action while reinforcements are summoned to converge on the battlefield for the purpose of surrounding and exterminating the raiders.