The nearest Tenth Army reserve was the 18th Division, away. Foch wrote that no-one had expected the DM to advance in an hour. The slow and piecemeal arrival of reserves was made worse by the failure of the supporting attack to the north by the British First Army, which was defeated on 9 May at the Battle of Aubers Ridge. Subsequently, the British offensive was postponed until the Battle of Festubert on 16 May which resulted in the capture of the village and an advance of . From 21 April to 25 May, the British Second Army was engaged against the German 4th Army, in the Second Battle of Ypres which diverted British resources from the First Army. After 11 May, the Tenth Army began methodical local attacks, in which tactically important ground was attacked piecemeal, until another general attack could be made on Vimy Ridge. First-class French divisions had lost many experienced soldiers, which reduced them to mediocrity; the methods of Note 5779 had not been adopted consistently and became a greater problem when replacement troops with no experience, tried to continue the offensive. The attempt in June to capture Vimy Ridge with another set-piece attack was a costly failure, despite the intervening period of local attacks on the flanks of XXXIII Corps and the capture of the Lorette Spur. French tactics were unchanged and the constant local attacks left no time for training. Revisions to the stipulations of Note 5779 in mid-June were of minor significance and an amendment of 18 June only referred to the importance of cavalry in mobile warfare. German defensive changes were easy to implement quickly and by June had made the French methods of May obsolete. For as long as the Germans were able to retain Souchez and Neuville, French attacks between them could not capture Vimy Ridge and the defences of the villages were too formidable to be overcome quickly. The original plan for a series of attacks might have been able to remove Souchez and Neuville as obstacles but the material constraints on the French in the spring of 1915, meant that the plan devised by Foch could not be implemented. In September Foch wrote of the speed with which the Germans had moved reinforcements into the area from 9 to 18 May, dug new defensive lines and brought more heavy artillery into action, which from 18 May maintained barrages along