Theodore Roosevelt (October 27, 1858 - January 6, 1919), often referred to by his initials TR, was an American statesman, author, explorer, soldier, naturalist, and reformer who served as the 26th President of the United States. A leader of the Republican Party, he was a leading force of the Progressive Era. He served as Assistant Secretary of the Navy under William McKinley, resigning after one year to serve with the First US Voluntary Cavalry Regiment or 'Rough Riders', gaining national fame for courage during the War in Cuba. During World War I, he opposed President Wilson for keeping the US out of the war against Germany, and offered his military services, which were never summoned. Although he planned to run again for president in 1920, his health quickly deteriorated, and he died in early 1919. Roosevelt has consistently been ranked by scholars as one of the greatest US Presidents. His face adorns Mount Rushmore alongside Washington, Jefferson, and Lincoln.