The Battle of Arras took place in France from 9 April to 16 May, 1917. It was fought by the British (First Army under Allenby, Third Army under Horne, Fifth Army under Gough) under the supreme command of General Haig against the heavily fortified line held by German Sixth and Second Armies.
After a massive artillery bombardment, British managed to advance in heavy fighting for up to 4.5 miles in some places—one of the largest gains since the start of the trench warfare. The most significant success was the capture of Hill 145, also known as Vimy Ridge by the Canadian Corps, a feature which dominated the surrounding landscape, and gave great military advantage to the force that occupied it. A total of 200 Mark IV tanks were promised to have been ready for this offensive, but as not a single one had in fact been produced, about 45 Mark II training tanks were used instead, their boiler plate sponsons replaced by armoured ones taken from Mark I wrecks.

Casualties surpassed 150,000 for the British, 100,000 for the Germans. No strategic breakthroughs were achieved.