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 {118} 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.
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THE REAR GUARD
A Rear Guard is essential to a force advancing in order to pick up the stragglers, to keep off marauders, and to prevent surprise by an energetic enemy who may detach a force for a surprise attack on the rear of the advancing column.
But its most important work is the protection of a retreating force, and this work will vary in difficulty with the freshness and enterprise of the enemy and the spirit and determination of the force that is being pursued. Generally speaking, Rear Guard fighting against an unexhausted enemy is the most difficult and most dangerous of all military enterprises. When a Rear Guard halts to fight it is being separated every minute from the Main Body, which is moving away from it, while every minute brings reinforcements to the enemy. The work requires great tactical skill, as it is the duty of the commander to delay pursuit by occupying positions from which he withdraws at the last moment, without becoming involved in a general engagement, from the meshes of which it may be necessary for the Main Body to return and extricate him. The work also requires great moral courage, as it is the duty of the commander to risk the loss of his force if by so doing he is adopting the only means of saving the Main Body.
STRENGTH.—The strength of the Rear Guard will depend upon the energy, strength, and closeness of the pursuit, the condition of the Main Body (and whether it is withdrawing voluntarily or upon compulsion after an unsuccessful engagement) and upon the nature of the country, but it will generally amount to not less than {120} one-fifth or more than one-third of the whole force, and will be selected, as a rule, from those who have been least severely engaged.
COMPOSITION.—Its composition depends upon the work to be performed, and this calls for detachments of all arms of the land service, in addition to Aircraft, which can prevent surprise by reconnaissance over the hostile area and can harass the pursuing columns by day and by night by fire-action with Lewis guns and bombs. Mounted troops are required to extend the area watched and to prolong the resistance by reason of their superior mobility, in addition to their counter-action as cavalry. Artillery are required to open long-range fire on the enemy's columns and so to cause delay by deployment; and to concentrate upon them while in, or emerging from, a defile. Infantry and Machine-gun Platoons are required for prolonged fire-fights and local counter-attacks, during which sudden bursts of machine and Lewis-gun fire will do the greatest execution. Engineers provide sappers for the creation of obstacles and traps, and for the demolition of bridges and viaducts. Mechanical Transport may be required to add to the mobility of the infantry. The Medical Service is called upon to provide attention and ambulances for the wounded and for the sick and worn-out troops.
DISTRIBUTION.—The Rear Guard is divided into two parts—the Rear Party and the Main Guard. The Rear Party consists, like the Vanguard of the Advanced Guard, of patrols and supports; the rest of the force forms the Main Guard, and marches in the order in which the troops are required, viz.: Artillery (with escort), Mounted Troops (if any remain over from the Rear Party), Infantry, Medical Services and Ambulances, and the Sappers of the Royal Engineers. The guns can thus open fire whenever required, and the sappers, who are furthest away from the pursuit, will have the longer time to prepare obstacles and demolitions, the {121} latter being completed by the Rear Party. Communication must always be secured and maintained between the Rear Party and the Main Guard, and between the Rear Guard and the Main Body.