 Complete the following phrase:  Foch ordered MaudHuy to slow the planned pace of the offensive, of successive attacks on several days, to ensure artillery support for the infantry, which was intended to substitute shells for lives. The offensive was fought from but despite the careful preparations achieved little. Artillery support was insufficient and rains turned the battlefield into a morass. XXI Corps managed a short advance and captured about of the German front trench and X Corps captured a small area of ground near Arras. The XXXIII Corps attack began next day and was equally frustrated by the German defence. Next day the corps concentrated its attack on Carency to little effect until 27 December, when of front-line trench was captured, only for most to be lost to a German counter-attack. Bad weather then delayed the offensive and on 5 January, Joffre decided to reinforce the Fourth Army, where the 