Kingdom of Castile at the beginning of the 13th century was economically weaker and politically less influential in compare to Aragon, while the Castilian government was concentrated on military campaigns against the Moors. Castile achieved the first major political success during the reign of Ferdinand III (1217-1252) who permanently united Castile and Leon after his father’s death in 1230. He also launched several military campaigns against the Moors and captured Cordoba and Seville, and made the Kingdom of Granada his vassal state.
Ferdinand’s son and successor Alfonso X the Wise (1252-1282) did pursue his father’s policy and was more interested in culture. He claimed the title of Holy Roman Emperor as grandson of Philip of Swabia in 1256 but he was more interested in Italy than Germany. He later renounced his claim to the Imperial crown and was not able to fulfill his plans in Italy due to inner political crisis and financial difficulties. Alfonso’s rule ended with his abdication in 1284. He was succeeded by his son Sancho IV (1284-1295) whose reign was marked by the dynastic struggles over the throne. He died in 1295 and his wife Maria de Molina acted as regent queen to her son Ferdinand IV (1295-1312) who was a minor at the time of his coronation. She was also a guardian to her grandson Alfonso XI (1312-1350) who was an infant at his accession to the Castilian throne in 1312.
Alfonso XI managed to restore the royal power which was greatly weakened under his predecessors and during his long minority. He launched several campaigns against the Moors and achieved a major victory in the Battle of Rio Salado in 1340. The reign of his successor Peter the Cruel (1350-1369) was marked by a civil war with Alfonso’s illegitimate son Henry of Trastamara. Peter was supported by the English, while Charles V of France sent his troops to aid Henry of Transtamara. However, Peter came into conflict with his English allies and thus the struggle ended with Peter’s deposition in 1369. His illegimate half-brother assumed the throne as Henry II (1369-1379).
The war for the succession also marked the reign of Henry’s successor John I (1379-1390). He claimed the throne of Portugal on the death of his father-in-law Ferdinand I of Portugal in 1383. The war for the Portuguese throne ended with Castilian defeat in the Battle of Aljubarrota in 1385, while Castile was invaded by the English forces led by John of Gaunt, 1st Duke of Lancaster shortly afterwards. The English invasion failed but John I finally ended the English threat by arrangement of the marriage of Henry III, his son and heir to the Castilian throne and Katherine of Lancaster, daughter of John of Gaunt in 1388. The reigns of Henry III (1390-1406), John II (1406-1454) and Henry IV (1454-1474) were characterized by the increased power of the Castilian nobility which virtually freed itself from the royal control during the reign of Henry IV.
Castilian throne was assumed by sister of Henry IV, Isabella I (1474-1504) and her husband Ferdinand II (1479-1516) on Henry’s death in 1474. Ferdinand II defeated Alfonso V of Portugal who claimed the Castilian throne and succeeded his father as King of Aragon in 1479. Thus Isabella and Ferdinand often referred as the Catholic Kings united Castile and Aragon, and created a basis for the political unification of Spain. Isabella I and Ferdinand II ended the Reconquista by conquest of Granada, the last Muslim stronghold in the Iberian Peninsula in 1492 and financed Christopher Columbus’ voyage to India which resulted in the discovery of America.