Francisco Xavier De Castanos, duke of Baylen, a Spanish general, born in Madrid about 1755, died there, Sept. 24, 1852. In early life he was sent with Gen. O'Reilly to the court of Frederick the Great to study the art of war, and on his return to Spain he entered the army. When Napoleon invaded Spain, Castailos was appointed captain general of the Spanish armies in Andalusia. At Baylen, July 19, 1808, he encountered a French force under Dupont, who were surrounded and after some fighting forced to capitulate on the 22d, surrendering 18,000 men. He was shortly after routed by Lannes at Tudela (Nov. 23, 1808), and resigning his command became a member of the regency. In 1811 he was appointed to the command in Estremadura and Galicia, in 1812 was placed by Wellington in charge of the fortress of Ciudad Rodrigo, and early in 1813 was given the command of one of the four armies into which the Spanish forces were then divided. He contributed to Wellington's victory at Vi-toria, but at the close of the year he was removed by the new regency, under the pretext that he was needed in the council of state.

After the restoration he was made captain general of Catalonia, an appointment which he resigned in 1816, but again accepted in 1823. In 1815 he was placed at the head of a force of 80,000 men destined to invade France, in 1833 received the title of duke of Baylen, and after Espartero's fall in 1843 became for a time the guardian of Queen Isabella. He became a senator in 1845.