The first attack of the Nivelle Offensive by the British First and Third armies came at Arras, north of the Hindenburg Line on 9 April and inflicted a substantial defeat on the German 6th Army, which occupied obsolete defences on forward slopes. Vimy Ridge was captured and further south, the greatest depth of advance since trench-warfare began was achieved, surpassing the success of the French Sixth Army on 1 July 1916. German reinforcements were able to stabilise the front line, using both of the defensive methods endorsed in the new German training manual and the British continued the offensive, despite the difficulties of ground and German defensive tactics, in support of the French offensives further south and then to keep German troops in the area while the Messines Ridge attack was being prepared. German casualties were British losses of the Third and First armies.