The Battle of Cambrai (20 November – 7 December 1917) was a British campaign of the First World War. Cambrai, in the Nord département (Nord-Pas-de-Calais), was a key supply point for the German Siegfried Stellung (part of the Hindenburg Line) and the nearby Bourlon Ridge would be an excellent gain from which to threaten the rear of the German line to the north. The operation was to include an experimental artillery action. Major General Tudor, Commander Royal Artillery (CRA) of the 9th Division, suggested trying out new artillery-infantry techniques on his sector of the front. During preparations, J. F. C. Fuller, a staff officer with the Royal Tank Corps (RTC), was in the process of looking for a place to use tanks as raiding parties. General Julian Byng, commander of the British Third Army, decided to incorporate them into the attack.

Date 20 November–7 December 1917 Location Cambrai, France Result British offensive success German counter-offensive recovery
Belligerents
British Empire  Newfoundland  United Kingdom  United States (30 November only)	German Empire  Baden  Bavaria  Prussia  Saxony  Württemberg
Commanders and leaders
Sir Julian Byng	Georg von der Marwitz
Strength
2 Corps 476 tanks (378 combat tanks)	1 Corps
Casualties and losses
c. 44,000 179 tanks	c. 45,000

The battle is often erroneously noted for being the first mass use of tanks in a combined arms operation. However, the French had deployed large numbers of tanks in April (130+), May (48) and October (92) 1917 and the British more than 200 in Flanders in June and July. Despite the initial success of the Mark IV tanks at Cambrai, German artillery and infantry defences exposed the frailties of their armour and the vehicles became mostly ineffective after the first day. The battle was largely an artillery-infantry engagement that achieved, surprise and technical superiority against strong fortifications but weak German infantry and artillery defences, which were quickly reinforced. The British attack demonstrated that the Hindenburg Line could be penetrated and showed the value of new artillery and infantry methods, such as sound ranging and infiltration tactics that would later play a vital part during the Hundred Days Offensive.

The popular perception of the battle as a tank battle was largely from writing by Basil Liddell Hart and J. F. C. Fuller, the latter erroneously claimed credit for the plan. Liddell Hart, whose position as Military Correspondent of the Daily Telegraph and The Times newspapers (1925–1939) gave him great public influence, was a critic of Douglas Haig and attempted to use the battle to indicate a "new" form of doctrine. Several modern studies have rejected their version of events and returned to a view nearer to that of the British Official History.