34. Harry S. Truman
President: Franklin Delano Roosevelt, 1945
Harry S Truman only met with FDR twice during his brief tenure as VP and he wasn't informed on most of the major policy debates going on with the war, including the Manhattan Project. When FDR died in April 12, 1945, Truman had one of the steepest learning curves of any job in recent memory. The “S” in Truman’s name, by the way, doesn’t stand for anything.