the Western Front. On 30 March, its Chief of Staff, Colonel Hans von Seeckt, recommended an offensive between Arras and Albert, requiring fourteen corps and artillery batteries. An offensive in the west was cancelled in April, due to the deteriorating situation on the Eastern Front, where the Austro-Hungarian Army (/) faced collapse. The 11th Army and other divisions of the were sent east and the initiative in the west was left with the Entente armies. The defences of the German army in the west had been improvised since late 1914 and in many places were vulnerable to the growing number of French heavy guns. During the spring, the began to build defences to a standard system, building a second position behind a barbed wire barricade, far enough behind the first position to require an attacker to pause to bring field artillery into range. The first position was elaborated into a zone, with camouflaged strong points and machine-gun nests built of concrete behind the front trenches. The 6th Army held a front of from Menin to the south of Arras with thirteen divisions and the 58th and 115th divisions in OHL reserve behind the front. The 6th Army had guns and guns. West of Lille, the front line was in the marshy Flanders plain and south of La Bassée, the ground was criss-crossed by waterways and drainage ditches, which made fortification difficult. West of Lens, the high ground of Vimy Ridge and the Lorette Spur dominated the ground further to the west; to the south, around Arras, the ground was overlooked from the ridge at Thilloy beyond the Scarpe. Prelude French preparations Since January French sappers in the Carency area had tunnelled , to plant of explosives in galleries under the German positions. The main French front of attack was from the chapel on the plateau of Notre Dame de Lorette Spur (Lorette spur) south to the , a network covering of trenches, tunnels and dug-outs across the Arras–Lens road north of Ecurie and Roclincourt. The spur was the southern boundary of the plain north of the Béthune–La Bassée Canal, which was long and wooded in parts, except at the east end. From the north the slopes of the ridge were low but on the south side there were steep spurs separated by ravines. West of Ablain St Nazaire (Ablain) was Spur Mathis and to the east, the Great Spur, the