The field artillery, under the orders of General Brock, the C.R.A., consisted of the 36th and 61st Divisional Artilleries and the 108th and 150th Army Field Artillery Brigades. For the creeping barrage there were fourteen 18-pounder batteries, giving, as at Messines, about one gun to twenty yards. There were four 18-pounder batteries for distant barrage, to search hidden ground, and deal with strong points beyond the creeping barrage, while the six 4.5 howitzer batteries fired a hundred yards ahead of the latter, resting on all known strong points and machine-gun emplacements. The pace of the barrage was a hundred yards in five minutes, with a pause of thirty-five minutes in front of the Green Line. This seems as slow as could well be, but events were to prove that it was too fast in the conditions. There were three gas-shell bombardments prior to the attack, the last being on the night of the 15th, "Y/Z" night. For these there was allotted a hundred rounds per 18-pounder and fifty rounds per howitzer. One section of tanks was to take part in the attack, but there was at no time a probability of tanks reaching our front line. Zero was at 4-45 a.m. There was very heavy shelling of the assembly trenches and the roads in rear during the night of the 15th. A small dug-out occupied by the headquarters of the 14th Rifles near Spree Farm was hit repeatedly, and it was impossible to keep alight a candle inside it. So excellent, however, was the German concrete, that it held out. Between midnight and 2-30 a.m. the four leading battalions must have suffered on an average fifty casualties apiece.