_Field Service Regulations_, Part I., 1909, speaking of the retreat says: “The cavalry and other mounted troops, aided by a strong force of artillery, will meanwhile check the enemy’s advance, and the remainder of the force, with the exception, if possible, of _a rear guard in support of the mounted troops_, will move as rapidly as possible to the shelter of the rallying position and there reorganise. Steps should be taken immediately _to secure any bridges, defiles, or other vital points on the line of retreat_ at which the enemy’s mounted troops might intercept the force. Commanders of retreating troops must recognise that their greatest danger will arise from attacks in flank delivered by the enemy’s mounted troops and horse artillery; if possible, therefore, they should take precautions _that all ground commanding their line of retreat is occupied by flank guards_.” There are three distinct ways of employing machine guns with infantry to assist in covering the retreat, as will be seen from the portions of the above quoted in italics, viz. (1) With the rear guard. (2) To secure vital points on the line of retreat. (3) To occupy commanding positions on the flanks. The use of machine guns with the rear guard will be dealt with separately, so we will see how they should be employed to fulfil the two latter duties. Let us suppose that the moment has arrived when the commander of the force decides to break off the engagement and to effect a retreat. We have already seen how the cavalry and their machine guns will co-operate, and we may assume that their intervention will enable the infantry to break off the fight under cover of the fire of the rear guard and their machine guns. In anticipation of this, the commander of the machine-gun batteries--other than those allotted to the rear guard--will assemble them in a central position and receive from the commander of the force his plan of action and instructions for the co-operation of the machine guns. These instructions should definitely state the positions to be occupied on the line of retreat, and for how long such positions are to be held (_e.g._ until the infantry are past such-and-such a place, or to the last possible moment, etc.); but they should leave all details as to unit of guns, fire positions, opening fire, etc., to the machine-gun commander, who should be given a free hand in carrying out his instructions. The machine-gun commander will then issue his orders to battery commanders, allotting the battery for the flank and the battery which is to occupy positions on the line of retreat. In like manner the battery commander will tell off sections to occupy certain positions, if these have already been selected, and if not he will direct his battery to a position of readiness and will gallop off with his section commanders to select the positions for each section and explain the course of action to be taken. The position of readiness must be in the vicinity of the