Late in March, the Canadian Corps was bolstered with the addition of the 3rd Canadian Division commanded by Major-General Mercer. On 1 June, the division would be involved in its first battle as the Germans launched an offensive at Mont Sorrel and Hill 61 and Hill 62, also known as Sanctuary Wood. The massive German artillery barrage that preceded the infantry assault killed Mercer. The 3rd Canadian Division was hurled back on 2 June. The following day, Major-General Arthur Currie's 1st Canadian division launched a hastily prepared counterattack that failed to retake Mont Sorrel, Hill 61, or Sanctuary Wood.
Major-General Currie, in a move that characterized his style of leadership and generalship throughout the war, demanded more time to properly prepare a second attack, and, on 13 June, the 1st Canadian Division launched a swift, well-coordinated offensive that regained all three locations. The accurate artillery barrage devastated the German positions, and the infantry assault was timed perfectly with the shelling. The barrage ended just as the Canadian troops approached the German trenches. Both Lieutenant-General Julian Byng, commander of the Canadian Corps, and Major-General Currie had demonstrated that patience and careful preparation were essential in the successful conduct of operations on a battlefield that had such a predominance of firepower. The successful action at Mont Sorrel marked the genesis of a particularly "Canadian" style of warfare on the Western Front, the precise coordination of accurate artillery fire with carefully planned infantry assaults. As the British Official History of the First World War would record, Mont Sorrell was Canada's first deliberately planned attack in any force," and it "had resulted in an unqualified success." The cost, however, was high: Canadian troops suffered 8,430 casualties at Mont Sorrel.