The Battle of Flers-Courcelette, which began on 15 September, 1916 and lasted for one week, was the third and last of the large-scale offensives mounted by the British Army during the Battle of the Somme. The battle is significant as the first use of the tank in warfare and expectations were high that it would prove a decisive weapon. However, the Mark I tank's performance in the battle was patchy and the British commander-in-chief, General Sir Douglas Haig, has been criticised for revealing the secret weapon too soon, something that he was warned against by both his subcommanders (such as E.D. Swinton ) and the French government that sent Colonel Jean-Baptiste Eugène Estienne and Subsecretary of State of Inventions Jean-Louis Bréton (normally arch-enemies) to London hoping to persuade the British government to overrule Haig.

Like the earlier offensives of 1 July (Battle of Albert) and 14 July (Battle of Bazentin Ridge), Haig had hoped to achieve a breakthrough of the German defences, enabling a return to mobile warfare. Though the British, Canadian and New Zealand forces did make significant gains on the day, a breakthrough was not forthcoming and the Somme front reverted to an attritional struggle, which, with the onset of wet weather, created dreadful conditions in which the infantry had to live and fight.

Objectives that were taken included High Wood and the Switch Line over which the British had been struggling for two months. On the left flank the Canadian Corps captured Courcelette while in the centre the villages of Martinpuich and Flers were taken but these were short of the original objectives of Gueudecourt and Lesboeufs . On the right, the German redoubt known as the Quadrilateral stopped the British well short of Morval . To take these remaining objectives, the British Fourth Army launched the Battle of Morval on 25 September.