Even before the war began , war hawks were demanding an invasion of canada. In july of 1812, american troops under General William Hull invaded Canada from Detroit. Hull was unsure of himself, fearing he did not have enough soldiers he retreated. General isaac Brock, a british commander, soldiers' .quickly surrounded hulls army and forced it to surrender.The British captured more than 2,00 american soldiers. it was a serious defeat for the united states.