The Canadian Corps were to capture the German-held high ground of Vimy Ridge, an escarpment on the northern flank of the Arras front. This would protect the First Army and the Third Army farther south from German enfilade fire. Supported by a creeping barrage, the Canadian Corps captured most of the ridge during the first day. The village of Thélus fell during the second day, as did the crest of the ridge, once the Canadian Corps overran a salient against considerable German resistance. The final objective, a fortified knoll outside the village of Givenchy-en-Gohelle, fell to the Canadians on 12 April. The 6th Army then retreated to the Oppy–Méricourt line.