confusion resulted from this, and many casualties were caused by the crews of machine-gun nests which were left undestroyed and so were in a position to fire from the rear upon our men, when the latter were sweeping forward to the attack of positions beyond them.
One other use of the guns which should be mentioned is the retaliatory barrage fired by the defender's Artillery. The plans for this barrage are carefully worked out beforehand in the event of an attack. As soon as news of the assault can be got back to the guns by S.O.S. signals, by the noise of the enemy's barrage, or by line or runner, all available guns are brought into action. These fire on pre-arranged objectives, with the idea of isolating the attacking troops, preventing supplies and reinforcements from reaching them, and inflicting as many casualties as possible during the earlier stages of their advance.
A fair example of the number of shells which are fired in a normal barrage is afforded from consideration of the barrage at the Battle of Bellenglise. Here on a 500-yard front, fifty-four 18-pounders and eighteen 4.5 howitzers were engaged in forming the barrage. Of these guns, the 18-pounders fired two rounds per minute and the howitzers one round per minute. The shells were fired to spread the bursts evenly along the barrage line, so that, in all, a total of 126 shells fell on a line 500 yards long within the minute, giving a total of one shell per four yards per minute. This barrage was kept up for eight hours and, allowing for slowing down of the rate of fire during the intervals when a stationary protective barrage was being fired, there cannot have been less than some 50,000 shells fired on this short frontage during the battle.
While five of the six Artillery Brigades attached to the Division fired in the enfilade barrage covering the main
