Theodore Roosevelt, Jr. (1858-1919), also known as T. R., and to the public (but never to friends and intimates) as Teddy, was the twenty-sixth ... Show synopsis Theodore Roosevelt, Jr. (1858-1919), also known as T. R., and to the public (but never to friends and intimates) as Teddy, was the twenty-sixth President of the United States, and a leader of the Republican Party and of the Progressive Movement. He became the youngest President in United States history at the age of 42. He served in many roles including Governor of New York, historian, naturalist, explorer, author, and soldier. Roosevelt is most famous for his personality: his energy, his vast range of interests and achievements, his model of masculinity, and his "cowboy" persona. He was the first American to be awarded the Nobel Prize, winning its Peace Prize in 1906, for negotiating the peace in the Russo-Japanese War. His The Naval War of 1812 (1882) was the standard history for two generations and his major achievement was a four-volume history of the frontier, The Winning of the West (1889-1896). His other works include Hero Tales from American History (1895), The Rough Riders (1899) and Hunting the Grisly and Other Sketches (1904).