

He remains the youngest person to become president of the United States. Roosevelt assumed the presidency at age 42 after McKinley was assassinated in September 1901. Roosevelt campaigned vigorously, and the McKinley–Roosevelt ticket won a landslide victory based on a platform of victory, peace and prosperity. The New York state party leadership disliked his ambitious agenda and convinced McKinley to make Roosevelt his running mate in the 1900 election. Returning a war hero, he was elected governor of New York in 1898. He resigned to help form and lead the Rough Riders, a unit that fought the Spanish army in Cuba to great publicity. He served as Assistant Secretary of the Navy under President William McKinley and in 1898 helped plan the highly successful naval war against Spain. He recuperated by buying and operating a cattle ranch in the Dakotas. His wife and mother both died in the same night and he was psychologically devastated. Upon entering politics, he became the leader of the reform faction of Republicans in New York's state legislature. His book The Naval War of 1812 (1882) established his reputation as a learned historian and popular writer. He was home-schooled and began a lifelong naturalist avocation before attending Harvard. He integrated his exuberant personality, a vast range of interests and achievements into a "cowboy" persona defined by robust masculinity.

Roosevelt was a sickly child with debilitating asthma but partly overcame his health problems by embracing a strenuous lifestyle. Having assumed the presidency after McKinley's assassination, Roosevelt emerged as a leader of the Republican Party and became a driving force for anti-trust and Progressive policies. He previously served as the 25th vice president under William McKinley from March to September 1901, and as the 33rd governor of New York from 1899 to 1900. R., was an American politician, statesman, conservationist, naturalist, historian, and writer who served as the 26th president of the United States from 1901 to 1909. ( / ˈ r oʊ z ə v ɛ l t/ ROH-zə-velt Octo– January 6, 1919), often referred to as Teddy or his initials T. Minority Leader of the New York State Assembly President of the New York City Board of Police Commissioners
