In March 1917 the Germans retreated to the Hindenburg Line which was a formidable series of defences that the Germans had constructed. In April the British launched the Arras Offensive and the Dublin Fusiliers took part in the two battles of the Scarpe that took place in April. The 10th Dublins took part in the Battle of Arleux (28–29 April) that saw the Dublins last involvement in a major battle of the Arras offensive. Half of the French Army, exhausted and angry at the enormous losses it had sustained, mutinied, refusing to fight unless it was to defend against German attacks. This compelled the British Army to take the leading role, and this would see the Dublin Fusiliers take part in further offensives before the year ended. In June, the Dublins took part in the capture of Wytschaete during the Battle of Messines. The Regiment's battalions subsequently took part in the Third Battle of Ypres (31 July –10 November), being involved in several of its subsidiary battles, including at Langemarck. As during Second Ypres, the Regiment suffered heavily, indeed the 9th Dublins had sustained such losses that they effectively ceased to be a fighting unit, and were amalgamated with the 8th Dublins in October, forming the 8th/9th Dublins. The Regiment's last major action of 1917 was a diversionary attack during the Battle of Cambrai (28 November – 3 December).