The 33rd Division relieved the 51st Division and on 11 August, continued to push sap heads forward towards the Switch line and dug a new trench closer to Wood Lane to the east. Two large flame-throwers and pipe-pushers (devices to force a pipe filled with explosives underground, parallel with the surface, to create a sap when the explosives were detonated) were brought forward, as both sides patrolled the area. On 18 August, a battalion of the 33rd Division attacked the wood, using the flame throwers and thirty oil drums thrown by Livens Projectors but the flame throwers failed and the projectors were buried by British artillery-fire which fell short; the pipe pushers fouled tree roots in the wood and one was deflected backwards, blowing a crater into the trench line of one of the attacking battalions. All attempts by the infantry to advance failed, although some troops broke into the German defences and were ejected by I Battalion, Infantry Regiment 134 and Infantry Regiment 104 recorded many casualties. On 20 August, the division attacked the wood with one battalion, to occupy a trench on the western edge of the wood. On 24 August, three battalions of the 100th Brigade attacked between High Wood and Delville Wood. On the night of the 1st Division relieved part of the 33rd Division and next day attacked on the east side of the wood, advancing a short distance. The rest of the 33rd Division was relieved by the 24th Division on 31 August. The largest German counter-attack of the Battle of the Somme, took place on the same day to the east of the wood, in the afternoon and evening. Troops of the II Bavarian Corps and XII Corps, pushed one battalion into the eastern side of the wood at Edge Trench.