defenders could close a gap quickly it would be necessary to maintain momentum, with reserve troops following up the attacking force closely. Attacks in open country were preferable to being bogged down in fighting for obstacles like villages and woods and the attack should be on a broad front, to allow centres of resistance to be outflanked and to disperse German firepower over a wider area. German analysis of the battle was collected in a memorandum of June 1915 and led to renewed emphasis on infantry shelters, deep enough to be invulnerable to heavy artillery and to increase the number of defensive positions behind the front, which would slow an advance and delay subsequent attacks, by forcing the attacker to move artillery into range. On 7 June a copy of Note 5779 was captured on the Artois front and the local corps commander ordered that intensive digging be undertaken and stipulated that reserve positions were to be as solidly built as front line defences. Much of the new digging on the rest of the Western Front was done on reverse slopes, invisible to ground observers and capable of being engaged only by howitzer-fire. The French methods of attack had been made obsolete by the time of the resumption of the offensive in September 1915, when many French troops were killed on such slopes, in front of uncut wire, before an undamaged second position. Casualties French sources put casualties from 3 May to 18 June at whom were killed; another were incurred in secondary operations. The German official historians of the recorded from 9 May to18 June, casualties and casualties. Sheldon recorded the same figures for French casualties, quoting the French official history and for the German divisions most involved in the battle (1st and 5th Bavarian Reserve divisions, 3rd Bavarian, 5th, 11th, 15th, 16th and 115th divisions) noting that some figures are estimates believed to be too low but that the total was far fewer than French losses. In 2013 Jonathan Krause recorded ranges of and casualties. Subsequent operations The battle had great influence on the French army during the preparations for the autumn offensive of 1915 in Champagne and Artois, which were also based on an assumption that strategic victories were possible after one or two days of offensive action. Joffre ordered another to double the number per brigade by 1 January 1916. Production of the 240 mm Trench