 The Royal Engineers immediately deployed specialist tunnelling companies along the front to combat the German mining operations.In response to increased British mining aggression, German artillery and trench mortar fire intensified in early May 1916.On 21 May 1916, after shelling both forward trenches and divisional artillery positions from eighty hidden batteries on the reverse slope of the ridge, the German infantry began , an attack on the British lines along a front to eject them from positions along the ridge.