The 4th Canadian Division faced difficulties at the start of the battle that forced it to delay its assault on the Pimple until 12 April. The Pimple was initially defended by the 16th Bavarian Infantry Division but the Canadian Corps' preliminary artillery bombardment leading up to the assault on 9 April caused heavy casualties amongst its ranks. On 11 April, the 4th Guards Infantry Division first reinforced and then relieved affected 16th Bavarian Infantry Division units. The night before the attack, artillery harassed German positions while a gas section of Royal Engineers, employing Livens Projectors, fired more than 40 drums of gas directly into the village of Givenchy-en-Gohelle to cause confusion. The defending German troops managed to drive back the initial Canadian assaults at around 4:00 am using small arms fire. The 10th Canadian Brigade attacked once again at 5:00 am, this time supported by a significant amount of artillery and the 24th Division of I Corps to the north. The German defensive artillery fire was late and too light to cause the assaulting troops great difficulty, allowing the Canadian Corps to exploit wide gaps and break into the German positions. The 10th Canadian Brigade, assisted by snow and a westerly wind, fought hastily entrained German troops to capture the entire Pimple by 6:00 pm.