122nd Siege Bty joined 78th HAG at Anzin-Saint-Aubin on 14 February and moved its guns into position north west of Arras two days later. Third Army was carrying out the artillery preparation for the Battle of Arras, with 78th HAG supporting XVII Corps. The main bombardment was planned to last for five days (V, W, X, Y and Z) beginning on 4 April. On 4 April one of 122nd Siege Bty's howitzers suffered a premature explosion of a shell in the barrel, destroying the gun, killing one gunner and wounding five others.The zone bombarded was divided into small zones without overlapping fire, to help the forward observation officers (FOOs) spot the fall of shot of their own guns. The 6-inch howitzers concentrated on the German second and third defence systems, destroying trenches and strongpoints and cutting barbed wire. Fire on targets was maintained at an even rate in daylight, with pauses for air reconnaissance. Harassing fire (HF) tasks were carried out at night. However, visibility was poor on some of the days, so an additional day (Q) was inserted on 7 April and Z day for the attack (the First Battle of the Scarpe) became 9 April.