Theodore Roosevelt Jr. ( ROH-zə-velt; October 27, 1858 – January 6, 1919), often referred to by his initials TR, was an American statesman, author, explorer, soldier, naturalist, and historian who served as the 26th President of the United States. A leader of the Republican Party, he was the spokesman for the Progressive Era. A sickly child whose asthma was debilitating and nearly fatal, Roosevelt regained his vigor, and embraced a strenuous life. He integrated his exuberant personality, vast range of interests, and world-famous achievements into a "cowboy" persona defined by its exultant masculinity. Home-schooled, he became a lifelong naturalist at an early age. Roosevelt attended Harvard College, where he studied biology, boxed, and developed an interest in naval affairs. His first of many books, The Naval War of 1812 (1882), established his reputation as both a learned historian and a popular writer. He soon entered politics, winning election to the New York State Assembly in 1881. He became the leader of the reform faction of the Republican Party in the state. Following the deaths of his wife and mother on the same day in 1884, Roosevelt took a reprieve from politics to operate a cattle ranch in the Dakotas as a cowboy. When his herds died in a blizzard he returned to run unsuccessfully for Mayor of New York City in 1886. He became New York City Police Commissioner in 1895, where he instituted major reforms. He served as Assistant Secretary of the Navy under William McKinley, resigning after one year to serve with the Rough Riders, gaining national fame for courage during the war in Cuba. The returning war hero was elected Governor of New York, but confronted an entrenched party establishment that distrusted him and pushed him into becoming McKinley's running mate in 1900. He stumped the nation, helping McKinley win by a landslide on a platform of peace, prosperity and conservatism.