Two portraits flank the doors leading into Canada's House of Commons: Sir Robert Borden to the left and W.L.M. King to the right. While each man appears flatteringly stern, wise, and charismatic, it is the portrait plaques that are of particular interest. Borden's caption reads: "World War I War Leader, 1914–1918," while King's caption is similar: "World War II War Leader, 1939–1945." No other dates are given. Perhaps that definition makes sense for Borden, who did little of note before the war; it does not ring true for King, Canada's longest serving prime minister. Yet in both cases world wars shaped their careers and legacies. They ushered in massive government changes: income tax, health care, and conscription; changes to society through industrialization, enfranchisement, and patriotic unpaid labour; and they raised enormous armed forces from a civilian base. Warlords is a fast-paced narrative that humanizes the war effort through the eyes of the prime ministers. Set against how our senior politicians governed themselves and the nation during these difficult times, it offers an invaluable perspective of war and war leaders.