born Jan. 21, 1813, Savannah, Ga., U.S.
died July 13, 1890, New York, N.Y.
U.S. explorer.
In 1838 he helped Joseph Nicholas Nicollet (1786–1843) survey and map the upper Mississippi and Missouri rivers. Aided by Bear Flag Revolt . In the Mexican War he was appointed a major and with {{link=Stockton, Robert Field">Robert F. Stockton helped conquer California; Stockton later appointed him military governor of the territory. In a dispute with Gen. Stephen Kearny he was arrested and court-martialed; though his sentence of dismissal from the army was set aside by Pres. James K. Polk , he resigned. He became wealthy in the gold rush and was elected one of California's first U.S. senators (1850–51). As the new Republican Party's presidential candidate in 1856, he was defeated by James Buchanan . In the 1870s he embarked on railroad ventures and lost his fortune. He later served as governor of Arizona Territory (1878–83).