The Battle of Vimy Ridge officially started at 5:30 AM on April 9th, 1917. The Canadians launched a creeping artillery barrage, which is a barrage of artillery shots that moved up the battlefield every minute. 20,000 Canadian soldiers from all four divisions followed this barrage closely. The Germans fought back with heavy machine guns placed on the German intermediate line. Each division was assigned to capture a certain part of the ridge for that day. The 1st, 2nd, and 3rd divisions all captured their part on schedule. The 4th division however, which was tasked with capturing Hill 145, which was the highest part of the ridge, and was a very important strategic point.
During the assault on Hill 145, the 4th Division started receiving fire from German soldiers on another important hill on the ridge known as the "Pimple". This caused massive losses for them and they were unable to capture the Hill on that day. The next day, the 4th Division, this time with help from brigades from other divisions, attacked and successfully captured Hill 145. On April 12th, two days later, the Canadians captured the Pimple, and essentially won the battle then and there.
During this battle, the Canadians gained more ground than in any other British offensive so far in the war. About 11,000 Canadian soldiers died in the Battle of Vimy Ridge. The victory at the ridge allowed the British to push the Germans further back in later battles, and served as a huge morale boost to the Canadian Army, and all the members of the Entente.