In London, Prime Minister William Pitt named Amherst as his new commander-in-chief of North America for 1759. The Louisbourg victory opened the St. Lawrence River to the British, and Amherst devised a three-pronged attack against French Canada: a push up the St. Lawrence to attack Quebec, another northward invasion from Albany by way of lakes George and Champlain, and pressure against the French in the west at Fort Niagara. The 1759 battle for Quebec City was fought on the Plains of Abraham and decided the future of Canada, as British forces under General James Wolfe defeated the French army of General Louis-Joseph Montcalm. Both generals were killed.