The Battle of Arras was a British offensive during the First World War. From 9 April to 16 May 1917, British, Canadian, New Zealand, Newfoundland, and Australian troops attacked German defences near the French city of Arras on the Western Front.

Date 9 April – 16 May 1917 Location Near Arras, France Result Indecisive; tactical Allied victory
Belligerents
British Empire United Kingdom Australia Canada  Newfoundland New Zealand	German Empire
Commanders and leaders
Douglas Haig Edmund Allenby Hubert Gough Henry Horne	Erich Ludendorff Ludwig von Falkenhausen Georg von der Marwitz
Strength
27 divisions in the assault	7 divisions in the line, 27 divisions in reserve
Casualties and losses
158,000	120,000–130,000

For much of the war, the opposing armies on the Western Front were at a stalemate, with a continuous line of trenches stretching from the Belgian coast to the Swiss border. In essence, the Allied objective from early 1915 was to break through the German defences into the open ground beyond and engage the numerically inferior German army in a war of movement. The Arras offensive was conceived as part of a plan to bring about this result. It was planned in conjunction with the French High Command, who were simultaneously embarking on a massive attack (the Nivelle Offensive) about eighty kilometres to the south. The aim of this combined operation was to end the war in forty-eight hours. At Arras the Allied objectives were to draw German troops away from the ground chosen for the French attack and to take the German-held high ground that dominated the plain of Douai.

The British effort was a relatively broad front assault between Vimy in the northwest and Bullecourt in the south-east. After considerable bombardment, Canadian troops advancing in the north were able to capture the strategically significant Vimy Ridge and British divisions in the centre were also able to make significant gains astride the Scarpe river. In the south, British and Australian forces were frustrated by the elastic defence and made only minimal gains. Following these initial successes, British forces engaged in a series of small-scale operations to consolidate the newly won positions. Although these battles were generally successful in achieving limited aims, these were gained at the price of relatively large numbers of casualties.

When the battle officially ended on 16 May, British Empire troops had made significant advances but had been unable to achieve a breakthrough.New tactics (embodied in SS. 135, Instructions for the Training of Divisions for Offensive Action and SS.143 Instructions for the Training of Platoons for Offensive Action) and the equipment to exploit them, with the platoon becoming the principal tactical unit, in four sections: Lewis gun, rifle grenade, bomber and rifle; with the creeping barrage, the graze fuze and counter-battery fire had been used, particularly in the first phase and had demonstrated that set-piece assaults against heavily fortified positions could be successful. This sector then reverted to the stalemate that typified most of the war on the Western Front.