text: Just before the battle, Falkenhausen had written that parts of the front line might be lost but the five  could be brought forward to relieve the front divisions on the evening of the second day. On 6 April, General Karl von Nagel, the 6th Army Chief of Staff, accepted that some of the front divisions might need to be relieved on the first evening of battle but that any penetrations would be repulsed with local immediate counter-attacks () by the front divisions. On 7 April, Nagel viewed the imminent British attack as a limited effort against Vimy ridge, preparatory to a bigger attack later, perhaps combined with the French attack expected in mid-April. Construction of positions to fulfil the new policy of area defence had been drastically curtailed by shortages of labour and the long winter, which affected the setting of concrete. The 6th Army commanders had also been reluctant to encourage the British to change their plans if the British detected a thinning of the front line. The Germans were inhibited by the extent of British air reconnaissance, which observed new field works and promptly directed artillery fire on them. The 6th Army failed to redeploy its artillery, which remained in lines easy to see and bombard. Work on defences was also divided between maintaining the front line, strengthening the third line and the new  (Drocourt–Quéant switch line) further back.
  Prelude
  British preparations