Walker, William, 1824–60, American filibuster in Nicaragua, b. Nashville, Tenn. Walker, a qualified doctor, a lawyer, and a journalist by the time he was 24, sought a more adventurous career. After a short stay in San Francisco, his filibustering expeditions began with an invasion of Lower California (1853–54) intended to wrest the region together with Sonora from Mexico. The invasion failed miserably. He was tried for violating neutrality laws but was acquitted by a sympathetic jury. In June, 1855, Walker set out on another filibustering expedition, this time to Nicaragua, at the invitation of one of the country's revolutionary factions. His capture of Granada brought an end to the fighting, and, after obtaining recognition (May, 1856) from the United States for the new government, Walker declared himself president of Nicaragua in July, 1856. An alliance of hostile Central American states and the enmity of his former friend Cornelius Vanderbilt, whose Accessory Transit Company controlled Walker's supply lines, led to his defeat and surrender to the U.S. navy in May, 1857. Considered a hero by many Americans, Walker was again acquitted of violating neutrality, but he then alienated U.S. public opinion by blaming his defeat on the U.S. navy. From the Islas de la Bahía of Honduras, Walker made a final abortive attempt (1860) to conquer Central America but was forced to surrender to the British navy. He was turned over to Honduras and was shot by a firing squad Sept. 12, 1860.
See his own book, War in Nicaragua (1860, repr. 1971); W. O. Scroggs, Filibusters and Financiers (1916, repr. 1969); L. Greene, The Filibuster (1937, repr. 1974); biography by A. H. Carr (1963).