Theodore Roosevelt had a sickly childhood but became one of the most popular US Presidents. He served as governor of New York and vice president under William McKinley before becoming president at age 42 after McKinley's assassination in 1901. As president, Roosevelt served two terms and helped end the Russo-Japanese War, winning the 1906 Nobel Peace Prize. After leaving office, he went on a safari in Africa and is memorialized on Mount Rushmore as one of America's most iconic leaders.