This is described in Nicholson Chapter IV.
Map updated October 14, 2007.

Nicholson Chapter IV: Festubert and Givenchy, 1915

Learning from the mistakes of the Battle of Aubers Ridge in May 1915, General Haig first used a systematic bombardment of the German defences prior to the infantry attack. At Aubers Ridge they had learnt the futility of pitting unsupported massed manpower against the skilfully applier German firepower. The CEF 1st Division landed over 100,000 artillery shells on the German defences, over a 60 hour period, prior to the infantry attack.