The moment that it is evident that a retreat is necessary it will be the duty of the Protective Cavalry commander immediately to collect all his cavalry, with a view to checking the enemy’s advance, and at the same time he should apply to the G.O.C. for as many machine guns as he can spare, and this is certainly the occasion when all the mounted machine-gun batteries should be sent to the commander of the rear guard. The first step will be to allot one or more batteries to the troops forming the two flank guards and to the main guard covering the centre. The general situation at this moment will of course govern their use. “The commander will determine, in accordance with the features of the ground, whether delay is best brought about by the occupation of positions blocking or flanking the enemy’s line of advance and the employment of fire action, or by a vigorous and timely attack by a body of horsemen. Frequently, however, opportunities may be offered for acting wide on the flanks, where even the threat of a mounted attack or a sudden dash from ambush may cause the enemy’s pursuit to be delayed without the force becoming too deeply committed.”[15] In either case the important thing for machine guns to do at this stage is quickly to seize ground from which to bring effective fire to bear across a wide extent of front. Dealing first with the commander of the batteries allotted to the centre, he will consult the O.C. cavalry and arrange with him his plan of action. It is of the first importance to stop the forward movement of the enemy on the direct line of retreat, as this is the easiest line of pursuit and the one upon which the most shaken portion of the troops will be found. The probable course of action for the machine guns here will be to break up into sections and form a line along the nearest feature of ground immediately in rear, from which fire can be brought to sweep the front and check direct pursuit. The more broken the country and the more commanding the ridge or other features, the more effectual will be the check, for at this stage guns will certainly be prominent in the pursuit and shelter from their fire will be very necessary.