The Battle of Arras was a British offensive on the Western Front during the First World War. From 9 April to 16 May 1917, British troops attacked German defences near the French city of Arras on the Western Front. The British achieved the longest advance since trench warfare had begun, surpassing the record set by the French Sixth Army on 1 July 1916. The British advance slowed in the next few days and the German defence recovered. The battle became a costly stalemate for both sides and by the end of the battle, the British Third Army and the First Army had suffered about 160,000 casualties and the German 6th Army about 125,000.

The Western Front was one of the main theatres of war during the First World War. Following the outbreak of war in August 1914, the German Army opened the Western Front by invading Luxembourg and Belgium, then gaining military control of important industrial regions in France. The German advance was halted with the Battle of the Marne. Following the Race to the Sea, both sides dug in along a meandering line of fortified trenches, stretching from the North Sea to the Swiss frontier with France, the position of which changed little except during early 1917 and again in 1918.