Whilst by the above we attempt to show that horse artillery is a most valuable accessory to cavalry in the attack, we believe it is even more efficacious in retreat. An artillery officer sent in advance of the rearguard can select various positions from which horse artillery, practically covered from view, can put a few shells into the mass of the enemy’s troops, as they pass some defile; or it may engage the hostile artillery in order to draw fire off the retreating cavalry, if the former exposes itself unduly. Meantime another section or battery is sent on, thus the action is taken up successively. In every case the ground should be selected so that it is (i.) possible to act in combination with the cavalry, and (ii.) withdraw without the enemy seeing the movement. Nor must it be forgotten that the enemy may engage in the “parallel pursuit,” consequently the wider the front shown by the force covering the retreat the better. Thus it may happen that, following the rule that in a retreat the most mobile troops should be farthest out to the flanks, a cross fire may be brought by two sections on the enemy’s pursuit. The drill regulations of German cavalry, 1909, impress the point ... that, should the issue of the battle prove unfavourable, the cavalry must strain every nerve to facilitate the retreat of the other arms. It is in just such cases that they must assume a restless offensive. Repeated attacks on the flanks of pursuing troops will produce the best results. In regard to the many other occasions on which horse artillery can assist cavalry they say: The horse artillery will often by its fire cause the foe to disclose his strength and thus help reconnaissance. In union with maxims it enables the opposition of the enemy in occupied positions and defiles to be overcome, and thus spares the cavalry a dismounted attack. Horse artillery and machine guns enable the cavalry to hem in at long range the enemy’s marching columns, to cause these to partially deploy through flank fire to change the direction of their march. Horse artillery is the one thing that prevents an enemy sitting still and thus preventing the cavalry factor of mobility asserting itself. CHAPTER XI CO-OPERATION OF HORSE ARTILLERY WITH CAVALRY IN THE GENERAL ENGAGEMENT “Cavalry has more need of artillery than infantry, because it cannot reply to fire, but can fight only with the steel.”--NAPOLEON.