Mahan, Alfred Thayer (1840-1914), a United States naval officer, called “the philosopher of sea power.” His aim was to show that command of the sea is a decisive factor in international relations. In The Influence of Sea Power upon History, 1660-1783 (1890), Mahan attributed the development of the British Empire to correct use of sea power.

Mahan urged the strengthening of the U.S. Navy to protect the nation's merchant shipping. He favored annexation of Hawaii and construction of a Central American canal. One of his supporters was Theodore Roosevelt. Many of Mahan's ideas were realized during and after the Spanish-American War (1898). His works were translated widely and influenced naval thought in Britain, Germany, and Japan.

Mahan was born in West Point, New York. His father, Dennis Hart Mahan (1802-1871), was a professor of engineering at the U.S. Military Academy and greatly influenced the course of study there. Young Mahan graduated from the Naval Academy in 1859 and saw action during the Civil War. Mahan was president of the Naval War College, 1886-89 and 1892-93. He retired in 1896, but was recalled during the Spanish-American War to serve on the board directing naval operations. He retired again in 1906, with the rank of rear admiral.

Mahan's other works include: The Influence of Sea Power upon the French Revolution and Empire, 1793-1812 (2 volumes, 1892); Life of Nelson (2 volumes, 1897); Sea Power in Its Relation to the War of 1812 (1905); From Sail to Steam (1907), an autobiographical work; Naval Strategy (1911); Major Operations of the Navies in the War of American Independence (1913).