At dawn the British First and Third Armies launched their great offensive at Vimy and Arras respectively. It had been prepared by a massive artillery bombardment greater than that at the Somme, and the infantry advanced more effectively under a creeping barrage. The attack succeeded in most of the areas and at Arras success was almost complete, taking the first two defensive systems. For the Canadians at Vimy Ridge this was the first time their four divisions fought together as a unified force and despite heavy losses this victorious day would be seen as key in their evolution from dominion to an independent nation.