The 756 medium and heavy guns and howitzers were organised in forty groups and the 1,510 field guns and howitzers in sixty-four field artillery brigades within the attacking divisions and thirty-three Army field artillery brigades, divided among the three attacking corps; 144000 long tons of ammunition was delivered, 1,000 shells for each 18-pounder, 750 shells per 4.5-inch howitzer, 500 rounds for each medium and heavy piece and another 120,000 gas and 60,000 smoke shells for the 18-pounder field guns.