The House of Trastamara was a dynasty of Spanish monarchs that ruled Castile from 1369 onwards and then Aragon, Navarre, and Naples from 1468 to 1555. The line of royalty originated with Henry II of Castile, who became king in 1366 due to his illegitimate descent from the House of Ivrea, the ruling family of Castile. The house would wrest power from Ivrea in the Castilian Civil War of 1366-1369, defeating Peter of Castile's forces and ending the House of Ivrea. The house remained in power in Castile alone for a century, when it expanded to rule Aragon, Navarre, and Naples; the Trastamara dynasty was the first to rule a united Christian Spain, and the house went extinct in 1555 with Joanna the Mad's death.