Juan Prim, count of Reus and marquis de los Castillejos, a Spanish general, born in Reus, Catalonia, Dec. 6, 1814, died in Madrid, Dec. 30, 1870. He early entered the army and the cortes, and in 1843 aided Narvaez in overthrowing Espartero, for which he was made a count, a general, and governor of Madrid. In the following year he turned against Narvaez, who caused him to be sentenced to six years' imprisonment; but the queen soon pardoned him and appointed him governor of Porto Rico. From 1848 to 1853 he was a parliamentary leader of the progresistas, and subsequently he lived in exile till 1858. In 1859-'60 he gained decisive victories as commander of the Spanish army in Morocco, especially at the battle of Los Castillejos, from which he took his title of marquis. In 1862 he commanded the Spanish force in Mexico destined to cooperate with France and England; but, unwilling to abet the designs of the emperor Napoleon, he withdrew together with the English, and his course was approved by the cortes. In August, 1864, he was for a short time expelled from Madrid on account of his alleged complicity in a military conspiracy; and in January, 1866, after his abortive rebellion against O'Donnell's administration, he fled, and fomented disturbances at home even while abroad.

In September, 1868, he brought about, with Serrano, Topete, and others, the revolution which drove Isabella from the throne, and became president of the council, minister of war, and commander-in-chief, with the rank of marshal, under Serrano's regency. After several vain attempts to find a foreign prince eligible for the throne, Prim fixed at last (July 2, 1870) upon Prince Leopold of Hohenzollern, which, through the jealousy of Napoleon III., resulted in the Franco-German war. He then prevailed upon the Italian prince Amadeus to become king, but was wounded by assassins on Dee. 28, and died on the same day on which Amadeus landed in Spain. A monument in his honor, cast in Paris, from drawings furnished by Zuloaga, a Spanish artist residing in France, was completed in 1875, to be placed over his tomb in the Atocha church at Madrid.