Early life Alfonso was born on 23 November 1221 in Toledo, Kingdom of Castile. He was the eldest son of
Ferdinand III and
Elizabeth (Beatrice) of Swabia. His mother was the paternal cousin of
Holy Roman Emperor Frederick II, to whom Alfonso is often compared. His maternal grandparents were
Philip of Swabia and
Irene Angelina. Little is known about his upbringing, but he was most likely raised in Toledo. For the first nine years of his life Alfonso was only heir to Castile until his paternal grandfather king
Alfonso IX of León died and his father united the kingdoms of Castile and
León. He began his career as a soldier, under the command of his father, when he was sixteen years old. After the accession of King
Theobald I of Navarre, Ferdinand tried to arrange a marriage for Alfonso with Theobald's daughter,
Blanche, but the move was unsuccessful. At the same time, he had a romantic relationship with
Mayor Guillén de Guzmán, who bore him a daughter,
Beatrice. In 1240, he married Mayor Guillén de Guzmán, but the marriage was later annulled and their issue declared illegitimate. During the 1240s, alongside his father, he conquered several Muslim strongholds in
Al-Andalus, including
Murcia,
Alicante and
Cádiz. In 1249, Alfonso married
Violant, the daughter of King
James I of Aragon and
Violant of Hungary, although betrothed already in 1246.
Reign Alfonso succeeded his father as King of Castile and León in 1252. The following year he invaded Portugal, capturing the region of the
Algarve. King
Afonso III of Portugal had to surrender. Despite this Afonso III reached an agreement with Alfonso X that in consenting to marry Alfonso X's daughter,
Beatrice of Castile, the captured land would be returned to their heirs. In 1261 Alfonso X
captured Jerez. In 1263 he returned Algarve to the King of Portugal and signed the
Treaty of Badajoz (1267). In 1254 Alfonso X signed a treaty of alliance with King
Henry III of England, supporting him in the war against King
Louis IX of France. In the same year Alfonso's half-sister,
Eleanor, married Henry's son
Edward: with this act Alfonso renounced forever all claim to the
Duchy of Gascony, to which Castile had been a pretender since the marriage of
Alfonso VIII of Castile to
Eleanor of England.
Imperial election In 1256, on the death of
William II of Holland, Alfonso's descent from the Hohenstaufen through his mother, a daughter of Philip of Swabia, gave him a claim to the German crown through the
Hohenstaufen line. Alfonso's election as
German king by the
prince-electors encouraged him to enter into complicated schemes that involved excessive expenses but never to success. Alfonso never travelled to Germany, and his alliance with the Italian
Ghibelline Lord
Ezzelino IV da Romano deprived him of the support of
Pope Alexander IV. His rival,
Richard of Cornwall, went to Germany and was crowned in 1257 at
Aachen. To obtain money, Alfonso debased the coinage and then endeavoured to prevent a rise in prices by an arbitrary
tariff. The little trade that took place in his dominions was ruined, and the burghers and peasants were deeply offended. His nobles, whom he tried to cow by sporadic acts of violence, rebelled against him in 1272. Reconciliation with the nobles was brought about by Alfonso's son Ferdinand in 1273. After Richard of Cornwell's death, the German princes elected
Rudolph of Habsburg (1273), Alfonso being declared deposed by
Pope Gregory X. In 1275 Alfonso tried to meet with his imperial vicar in Italy,
William VII of Montferrat (who had succeeded Ezzelino), and his Ghibelline allies in
Piedmont and
Lombardy to celebrate the victory against the Guelph
Charles I of Anjou and be crowned in Lombardy. However, he was halted in his imperial ambitions in Provence by the Pope who, after a long negotiation, obtained Alfonso's oral renunciation of any claims to the Holy Roman Empire.
Civil war Throughout his reign, Alfonso contended with his nobles, particularly the families of
Nuño González de Lara,
Diego López de Haro and
Esteban Fernández de Castro, all of whom were formidable soldiers and instrumental in maintaining Castile's military strength in its frontier territories. According to some scholars Alfonso lacked the singleness of purpose required by a ruler who would devote himself to organization and also the combination of firmness with temper needed for dealing with his nobles although this is not a view taken by all. Others have argued that his efforts were too singularly focused on the diplomatic and financial arrangements surrounding his bid to become Holy Roman Emperor. , from the
Cantigas de Santa María Alfonso's eldest son,
Ferdinand, died in 1275 at the
Battle of Écija against the Moroccan and
Granadan invasion armies, leaving two infant sons. Alfonso's second son,
Sancho, claimed to be the new heir, in preference to the children of Ferdinand de la Cerda, basing his claim on an old Castilian custom, that of
proximity of blood and
agnatic seniority. Alfonso preferred to leave the throne to his grandsons, but Sancho had the support of the nobility. A bitter civil war broke out resulting in Alfonso's being forced in 1282 to accept Sancho as his heir instead of his young grandsons; only the cities of
Seville,
Murcia and
Badajoz remained faithful to him. Son and nobles alike supported the
Moors when he tried to unite the nation in a crusade; and when he allied himself with
Abu Yusuf Yakub, the ruling
Marinid sultan of Morocco, they denounced him as an enemy of the faith. A reaction in his favour was beginning in his latter days, but he died defeated and deserted at Seville in 1284, leaving a will, by which he endeavoured to exclude Sancho, and a heritage of civil war.
Economic policy In 1273, he created the
Mesta, an association of some 3,000 petty and great sheep holders in Castile, in reaction to less wool being exported from the traditional sites in England. This organization later became exceedingly powerful in the country (as wool became Castile's first major exportable commodity He began one of medieval Europe's most comprehensive law codes, the
Siete Partidas, which, however, thwarted by the nobility of Castile, was only promulgated by his great-grandson. Because of this, and because the
Partidas remain fundamental law in the American Southwest, he is one of the 23 lawmakers depicted in the House of Representatives chamber of the
United States Capitol.
Military training of Alfonso X of CastileFrom a young age Alfonso X showed an interest in military life and chivalry. In 1231 Alfonso traveled with Pérez de Castron on a military campaign in lower Andalusia. Writing in
Estoria de España, Alfonso describes having seen
St. James on a white horse with a white banner and a legion of knights fighting a war above the soldiers of Spain. This vision of a heavenly army fighting in Jerez and participation in military campaigns likely left Alfonso X with a high degree of knowledge and respect for military operations and chivalric knights. Alfonso's respect for chivalry can also be seen in his writing of Spanish law. Spanish Chivalric conduct was codified in the (2,21) where he wrote that knights should be, "of good linage and distinguished by gentility, wisdom, understanding, loyalty, courage, moderation, justice, prowess, and the practical knowledge necessary to assess the quality of horse and arms (, 21,1–10)." These efforts to make a codified standard of chivalric conduct were likely meant to both encourage strength of arms (prowess) and to restrain the use of violence for only
just (state-sponsored) usage. ==Court culture==