Soulé, Pierre (pyĕr sōlāˈ) [key], 1801–70, American political leader and diplomat, b. Castillon, France. A lawyer, he was imprisoned for republican activities against the conservative Bourbons, but he escaped and fled (1825) to the United States. He ultimately became a citizen of New Orleans and a power in the Democratic party in Louisiana. Soulé served in the U.S. Senate in 1847 and from 1849 to 1853, when he resigned to become minister to Spain. Instructed to try to secure Cuba from Spain, he overreached himself, especially in drawing up, with James Buchanan and John Y. Mason, the notorious Ostend Manifesto. After its repudiation by the United States, he resigned (Dec., 1854). In the Civil War he served (1863–64) in the Confederate government at Richmond in a minor capacity.