with which they can traverse and sweep widely extended lines, and instantly concentrate fire on any portion of it, make them of great service in covering a retirement at effective range, as they can render the hottest fire ineffective and aimed fire impossible for a short time.
Machine guns with a rear guard must be prepared to work from place to place with great rapidity, and for this purpose they must arrange to bring the gun horses close up to their fire position. Alternative positions are essential, but must be reached under cover and unobserved by the enemy. Sections will act independently, using their guns in mutual support; but the retirement of one section may often afford another the opportunity, from a well-chosen position on a flank, to surprise the enemy from close range as they press forward to occupy the abandoned position.
A ruse that may sometimes be successful where guns are really well concealed is to bring up the gun horses and retire at a gallop by a pre-arranged signal all along the position, but leaving one gun of each section still in position but flat on the ground, where it will be completely concealed even from glasses. This is almost certain to draw a hot pursuit, especially if the artillery and infantry have retired previously, and if fire is reserved till close range a severe check may be administered to the enemy. "Skilfully laid ambushes will cause the enemy to move with caution in pursuit."[A]
