Claim: Theodore Roosevelt was a naturalist advocate.

Theodore Roosevelt Jr. -LRB- -LSB- ˈroʊzəvɛlt -RSB- ; October 27 , 1858 -- January 6 , 1919 -RRB- was an American statesman , author , explorer , soldier , naturalist , and reformer who served as the 26th President of the United States from 1901 to 1909 . He also served as the 25th Vice President of the United States and as the 33rd Governor of New York . As a leader of the Republican Party during this time , he became a driving force for the Progressive Era in the United States in the early 20th century . His face is depicted on Mount Rushmore , alongside those of George Washington , Thomas Jefferson , and Abraham Lincoln .   Roosevelt was born a sickly child with debilitating asthma , but he successfully overcame his physical health problems by embracing a strenuous lifestyle . He integrated his exuberant personality , vast range of interests , and world-famous achievements into a `` cowboy '' persona defined by robust masculinity . Home-schooled , he began a lifelong naturalist avocation before attending Harvard College . His book , The Naval War of 1812 -LRB- 1882 -RRB- , established his reputation as both a learned historian and as a popular writer . Upon entering politics , he became the leader of the reform faction of Republicans in New York 's state legislature . Following the near-simultaneous deaths of his wife and mother , he escaped to a cattle ranch in the Dakotas . Roosevelt served as Assistant Secretary of the Navy under President William McKinley , but resigned from that post to lead the Rough Riders during the Spanish -- American War . Returning a war hero , he was elected Governor of New York in 1898 . After the death of Vice President Garret Hobart , the New York state party leadership convinced McKinley to accept Roosevelt as his running mate in the 1900 election , moving Roosevelt to the prestigious but powerless role of vice president . Roosevelt campaigned vigorously and the McKinley-Roosevelt ticket won a landslide victory based on a platform of peace , prosperity , and conservatism .   Following McKinley 's assassination in September 1901 , Roosevelt became president at age 42 , and remains the youngest president . As a leader of the Progressive movement , he championed his `` Square Deal '' domestic policies , promising the average citizen fairness , breaking of trusts , regulation of railroads , and pure food and drugs . Making conservation a top priority , he established a myriad of new national parks , forests , and monuments intended to preserve the nation 's natural resources . In foreign policy , he focused on Central America , where he began construction of the Panama Canal . He expanded the Navy and sent the Great White Fleet on a world tour to project the United States ' naval power around the globe . His successful efforts to broker the end of the Russo-Japanese War won him the 1906 Nobel Peace Prize . He avoided the controversial tariff and money issues . Elected in 1904 to a full term , Roosevelt continued to promote progressive policies , but many of his efforts and much of his legislative agenda were eventually blocked in Congress . Roosevelt successfully groomed his close friend , William Howard Taft , and Taft won the 1908 presidential election to succeed him . In polls of historians and political scientists , Roosevelt is generally ranked as one of the five best presidents .   Frustrated with Taft 's conservatism , Roosevelt belatedly tried to win the 1912 Republican nomination . He failed , walked out , and founded a third party , the Progressive , so-called `` Bull Moose '' Party , which called for wide-ranging progressive reforms . The split allowed the Democrats to win the White House and a majority in both houses of Congress . Following his election defeat , Roosevelt led a two-year expedition to the Amazon basin , where he nearly died of tropical disease . During World War I , he criticized President Woodrow Wilson for keeping the country out of the war with Germany , and his offer to lead volunteers to France was rejected . Though he had considered running for president again in 1920 , Roosevelt 's health continued to deteriorate , and he died in 1919 .