Theodore Roosevelt was an American politician who served as the 25th President of the United State s (1905 - 1913). He is regarded highly by many Americans for his robust patriotism and progressive reforms. Elected in a landslide in 1904, and again in 1908 he increased the size of the US army and Navy and introduced the doctrine of "big stick diplomacy" that would be at the forefront of US foreign policy until 1921.