Aside from FDR, no American did more to shape World War II than Admiral William D. Leahy–not Douglas MacArthur, not Dwight Eisenhower, and not even the legendary George Marshall. No man, including Harry Hopkins, was closer to Roosevelt, nor had earned his blind faith, like Leahy. Through the course of the war, constantly at the president's side and advising him on daily decisions, Leahy became the second most powerful man in the world.