and three others all supporting the French. The C. P. O.'s were directed against the enemy front lines in case he were caught forming for an attack. They were called C. P. O. General, C. P. O. Redoute, and C. P. O. Apremont, C. P. O. Varnieville, C. P. O. Bis, C. P. O. 4 and C. P. O. T. C. P. O. General was the most important of these. It "combed" an area 200 metres in depth over the Boche front lines. The concentrations were directed at sensitive points behind the lines such as junctions of trenches, machine gun posts, dugouts, or important communication trenches.

                During the twenty days that we occupied this position, 12 C. P. O.'s, 21 concentrations, and 13 barrages were Fired. Also cross roads were shelled 13 times, important trenches 24 times, and the guns were registered 13 times. Owing to the range, (the guns being 5,500 meters from the lines) we could en­ gage in no counter-battery work.

                The rates of fire for a barrage or C. P. O. as well as the barrage signals varied frequently. At first the barrage rate was six rounds per piece per minute for three minutes, three rounds per piece per minute for three minutes, one round per piece per minute for one minute, a total of 124 rounds in seven minutes. Later the rate changed to six rounds per piece per minute for four minutes, two rounds per piece per minute for four minutes. The original C. P. O. rate was four rounds per piece per minute for Ave minutes, two rounds per piece per minute for ten minutes, for a total of 160 rounds in 15 minutes. Barrages were called for by telephone or by rocket. In case of at­ tack, the Infantry would fire a rocket from the front

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