number of divisions employed by the Germans from March 21 to April 23, 1918, against the British alone was 102 (approximately 1,500,000 troops), and many of them were thrown in twice or three times. "In resisting the heavy blows which such a concentration of troops has enabled the enemy to direct against the British Army, all ranks, arms, and services have behaved with a gallantry, courage, and resolution for which no praise can be too high" (Haig's Dispatch). COVERING FIRE.--The energetic and determined support of the infantry by fire is the main duty of machine-gun units throughout the whole course of the battle. In the attack, machine-gun platoons, Lewis gun sections, {44} or rifle sections detailed to give covering fire, must take care to select as targets those bodies of the enemy whose fire is chiefly checking the advance. Machine-gun platoons are sometimes brigaded, and at others left to battalion commanders, and their action after a temporary success in providing covering fire may depend upon their tactical distribution at the time. Infantry platoons detailed to give covering fire must join in the advance as soon as their own fire ceases to be effective in aiding the forward troops, unless definite orders to the contrary have been received. FIRE AND MOVEMENT.--It is thus seen that Fire and Movement are inseparably associated, and judiciously employed in combination they enable infantry to achieve its object in battle, to bring such a superiority of fire to bear as to make an advance to close quarters possible, so that the enemy may be induced to surrender or may be overwhelmed by a bayonet assault; and to prepare by similar means for further advances, until the enemy is entirely hemmed in or completely routed. [1] In fiction, this point (that the generalissimo must not allow his sense of proportion to be distorted by local successes or reverses) is clearly brought out in _The Point of View_, a story in "The Green Curve" by Ole-Luk-Oie (General Swinton). {45} TYPES OF BATTLE ACTION A battle must practically always be of the nature of Attack and Defence, but the attitude originally assumed by either of the opposing forces may be reversed during an engagement. A vigorous counter-attack by an army offering battle in a defensive position may throw the adversary on the defensive, while an assailant may fight a delaying action in one part of the field, although in another part his action may be essentially offensive. There are three distinct systems of Battle Action: the entirely defensive; the entirely offensive; and the combined, or defensive-offensive system.