on the explosion, the assaulting troops had to be formed up 60 yards in rear of their own trenches. To lessen casualties as far as possible it was necessary for the assaulting companies to be on the German side of our trenches before they started this barrage - in the case of the 5th Fusiliers who advanced their companies in four lines, the last company just managed to get over our trenches before the barrage began & their casualties were slight compared to the Royal Fusiliers. The latter were fired on directly they attempted to cross our parapets & lost very heavily. The mine explosions were to be the signal for the assault & for our artillery to form their prearranged barrage. It is estimated that about 200 Germans were killed in the explosion alone.