Ferdinand III (Spanish: Fernando III), 1199/1201 – 30 May 1252, called the Saint (el Santo), was King of Castile from 1217 and King of León from 1230 as well as King of Galicia from 1231.
He was the son of Alfonso IX of León and Berenguela of Castile.
Through his second marriage he was also Count of Aumale.
Ferdinand III was one of the most successful kings of Castile, securing not only the permanent union of the crowns of Castile and León, but also masterminding the most expansive campaign of Reconquista yet.
By military and diplomatic efforts, Ferdinand greatly expanded the dominions of Castile into southern Spain, annexing many of the great old cities of al-Andalus, including the old Andalusian capitals of Córdoba and Seville, and establishing the boundaries of the Castilian state for the next two centuries.
Ferdinand was canonized in 1671 by Pope Clement X and, in Spanish, he is known as Fernando el Santo, San Fernando or San Fernando Rey.
Places such as the cities of San Fernando, Pampanga and San Fernando, La Union; the Diocese of Ilagan and the San Fernando de Dilao Church in Paco, Manila in the Philippines; and in California, United States, the City of San Fernando and the San Fernando Valley, were all named after him (namesakes) and placed under his patronage.