One month after transferring the Canadian Corps to the Vimy Ridge sector in November 1916, General Sir Douglas Haig, the British Commander-in-Chief, assigned it the daunting task of taking the German position. The attack would not be the first Allied attempt to seize the stronghold; the French had committed 20 divisions (a division was approximately 20,000 men) in their largest assault. The French suffered 150,000 killed and wounded, yet the Germans had held firm.
The Canadian Corps commander, Lieutenant-General Julius Byng, and Major-General Arthur Currie, commander of the 1st Canadian Division, made meticulous plans for the offensive. The assaulting troops spent days carefully rehearsing their attacks in the rear where the enemy trench lines had been reproduced on the ground. The Canadians plotted the location of the main German artillery batteries using the techniques of sound ranging and "flash spotting." Sound ranging used acoustic equipment to measure the distance and direction of artillery batteries when they fired. Flash spotting was done at night. Observers in different locations would record the bearings of artillery flashes, then use triangulation to determine the exact location of German artillery. The Canadian Corps machine gunners had proven by this time that they could engage indirect targets just like artillery. In the days prior to the assault, the Canadian artillery stopped firing at night in order to avoid giving away its own positions. Instead, machine guns fired indirect fire barrage targets. As a result, the Germans were not able to repair the damage done by the artillery in the daytime. Canadian infantry also conducted several trench raids that provided valuable information on the German entrenchments.
On 9 April, the Canadian artillery unleashed an intense barrage in which 6 million shells rained down on the German defences; two thirds of the shells concentrated on the German artillery positions. The Canadian troops then surged forward in the dawn hours and overwhelmed the shaken German defenders. The coordination of the assaulting infantry with the creeping artillery barrage and machine gun fire was flawless. By noon, the ridge was in Canadian hands, and a gaping hole had been made in the German defences. The Canadian forces had accomplished in 10 hours what the British and French had failed to achieve in 2 years.
Vimy Ridge was the first major Allied victory on the Western Front since 1914, and it was recognized as a Canadian achievement in Britain and France as well as in Canada.