On the day William is listed as being killed in action, 16th May 1915, an assault on the enemy lines was launched. The Battalion commenced to file into the front trenches of the British line north of Rue de Cailloux. The enemy by this time had opened up a heavy bombardment. The barricade on the Rue de Cailloux was demolished and an opening made in the parapet. From 4.30 am the A, B, C and D Companies of the Battalion reinforced other units in the front line trenches, where it was possible, as enfilade fire made the occupation of some trenches untenable. At dusk the Battalion was ordered to hold the first German trench.

On the map this is the brown line from the Rue des Cailloux to La Quinque Rue. The war diary states that "All companies attacked ‘with great dash and quickness’ and the complex action took place from 2.00am until 8 pm when, after 18 hours of fighting, the survivors left the field to proceed to new billets. Casualties of officers and men were 26 killed, 160 wounded and 21 missing"