Ypres east of the town. The first gas attack occurred against Canadian, British, and French soldiers, including both metropolitan French soldiers as well as Senegalese and Algerian tirailleurs (light infantry) from French Africa. The gas used was chlorine. Mustard gas, also called Yperite from the name of this town, was also used for the first time near Ypres, in the autumn of 1917. Of the battles, the largest, best-known, and most costly in human suffering was the Third Battle of Ypres (31 July to 6 November 1917, also known as the Battle of Passchendaele), in which the British, Canadian, ANZAC, and
Action of 25 September 1917 increase the accuracy of German artillery-fire as the British attacked. On 23 September, Crown Prince Rupprecht wrote in his diary that the higher ground at Zonnebeke and Gheluvelt was vulnerable to another British attack and that it was vital that the German counter-attack tactic did not fail again. Next day, Rupprecht wrote that he hoped that another British attack would be delayed, as the 4th Army had insufficient reserves for the whole of the active front east of Ypres. Rupprecht ordered a (methodical counter-attack) against the British flank between the Menin Road and Polygon Wood, which was longer after the