Vimy Ridge was a keystone of German defenses on the northern flank of the western front. Numerous assaults had been made against, all failures. In 1917, the tasked of taking the ridge was given to the newly-created Canadian Corps. Backed up by a huge concentration of artillery and aircraft, and benefiting from rehearsals down to company level, the Canadians pulled off one of the most successful attacks of the year. However, determined German defenders checked the Canadians to prevent any significant advance beyond the ridge.