According to historian G. W. L. Nicholson, "The Somme offensive had no great geographical objectives. Its purpose was threefold – to relieve pressure on the French armies at Verdun, to inflict as heavy losses as possible on the German armies, and to aid allies on other fronts by preventing any further transfer of German troops from the west." The Canadian Corps was formed after receiving the 2nd and 3rd and later, 4th divisions. Its first commander was Lieutenant-General Edwin Alderson, who was soon replaced by Lieutenant-General Julian Byng, in time to repulse a German attack at Mont Sorrel in the Ypres sector in June 1916. while much of the BEF was moving toward the Somme. In this engagement, Major-General Malcolm Mercer, commander of the newly formed 3rd Division was killed; he was the most senior Canadian to be killed in the war.