Arabs' Spur, the Spur of the White Way and the Spur of Souchez, which dominated the east edge of Ablain and the sugar refinery between Ablain and Souchez. By 20 March the French had worked their way up to the foot of the Great Spur and by 14 April had closed up to Ablain. General d'Urbal was appointed to the command of the Tenth Army on 2 April, which had six infantry corps, a cavalry corps and three divisions in reserve. On the right (southern) flank was X Corps with the 19th and 20th divisions, the XVII Corps to the left with the 34th and 33rd divisions, XX Corps with the 11th and 39th divisions, XXXIII Corps with the Moroccan, 70th and 77th divisions, XXI Corps with the 13th and 43rd divisions and IX Corps with the 92nd Territorial Division and the 17th and 58th divisions, covering the ground up to the British First Army to the north. The IX Corps and XX Corps had been relieved by the British in Flanders and moved south from 9 to 16 April, although the IX Corps headquarters and the 18th, 152nd and 153rd divisions had to be rushed up to Flanders after the German gas attack at the Second Battle of Ypres Artillery reinforcements increased the quantity of heavy artillery to and field artillery to Increased production of ammunition had not kept pace with demand and the French artillery remained short of high explosive shells; poor quality ammunition also caused a large number of premature detonations in French artillery. French plan The Tenth Army was to attack on a front, the main attack being made in the centre by the XVII, XX and XXXIII corps on a front, with supporting attacks along the spur south of Bailleul-Sir-Berthoult and by the XXI Corps with two divisions along the Notre-Dame de Lorette spur. The main attack was to capture Vimy Ridge and then consolidate to prevent German counter-attacks from recapturing the heights. Reserve divisions and cavalry would then begin a pursuit from the ridge into the Douai plain. D'Urbal wanted a four-hour artillery bombardment to surprise the German defenders but this was over-ruled by Foch and Joffre. A four-day bombardment was substituted, based on the experience of the offensives of the winter and early spring (especially the St Mihiel offensive). Delays in the arrival of artillery led to a postponement of the attack from