See also Alfonso V, King of Aragón,
The Magnanimous; Ramón Berenguer IV,
Count of Barcelona
Further Reading
Lacarra, J. M. Historia del reino de Navarra en la Edad Media.
Pamplona, 1975.
O’Callaghan, J. F. A History of Medieval Spain. Ithaca, N.Y.,
1975.
Pérez de Urbel, J. Sancho el Mayor de Navarra. Madrid, 1950.
Theresa Earenfight
SANCHO IV, KING OF CASTILE
(1258–1295)
Sancho IV, the second son of Alfonso X and Queen
Violante, was born on 12 May 1258 in Valladolid. His
sobriquet, “el Bravo,” referred to his strength of will
and determination. After the sudden death of his older
brother Fernando de la Cerda in 1275, Sancho, reject-
ing the claims of his nephew, Alfonso de la Cerda, and
demanded recognition as heir to the throne. Although
Alfonso X acknowledged him, continual pressure from
France and the papacy led the king to propose giving
a portion of his dominions to his grandsons, Alfonso
and Fernando, known collectively as the Infantes de la
Cerda. Breaking with his father, Sancho, with the con-
sent of the estates of the realm assembled at Valladolid
in 1282, assumed royal authority, though he did not
take the crown. A desultory civil war followed until the
death of Alfonso X on 4 April 1284. Unreconciled and
disinherited by his father, Sancho IV, nevertheless, was
acclaimed as king and crowned at Toledo.
His situation was exceedingly precarious. Not only
did Alfonso de la Cerda, supported by France, dispute
his claim to the throne, but the pope had excommuni-
cated Sancho and placed an interdict on his kingdom.
The pope also denied the legitimacy of his marriage to
his cousin, María de Molina; thus, their children would
be considered illegitimate and lack any claim to inherit
the throne. By challenging his father and by making
many promises that he was unable to carry out, Sancho
IV also weakened the authority of the crown.
Throughout his reign he was engaged in an intense
struggle to gain control of the straits of Gibraltar in
order to prevent any Moroccan invasion in the future.
Immediately after his accession he had to provide for the
defense of the southern frontier against a new challenge
by Abu ̄ Yu ̄ suf, the Merinid emir, Alfonso X’s last ally.
Landing at Tarifa in April 1285, he besieged Jerez while
his troops devastated a broad zone from Medina Sidonia
to Carmona, Écija, and Seville. While Sancho IV sent
his Genoese admiral, Benedetto Zaccaria, to protect the
mouth of the Guadalquivir, a Castilian fl eet of about one
hundred ships waited in the straits to relieve Jerez or to
disrupt the emir’s communications with Morocco. When
Sancho IV marched southward from Seville to Jerez,
Abk Yk suf decided not to test his fortunes in battle,
and retreated to the safety of Algeciras in August. Two
months later Sancho IV made peace with the emir.
Meanwhile, after the failure of the French crusade
against Aragón, Sancho IV, because of continuing
concern over the claims of Alfonso de la Cerda, was
under pressure to enter an alliance with either kingdom.
On the one hand, Philippe IV of France was Alfonso’s
cousin while Alfonso III of Aragón had custody of the
two Infantes de la Cerda. Lope Díaz de Haro, lord of
Vizcaya, who had much to do with securing Sancho IV’s
recognition as heir to the Castilian throne, preferred the
alliance with Aragón as a guarantee that Alfonso de la
Cerda would not be free to press his claims. Lope was
the most infl uential person in the realm because the king
had given him control over the royal household and fi -
nances as well as custody of all royal strongholds. Other
members of the royal council eventually convinced
Sancho IV that he had entrusted Lope with far too much
authority. Thus the king turned against him in 1288 and
caused his death in a violent scene.
Now free to decide for himself, Sancho IV broke
with Aragón and allied with France. He expected that
the continual threat of French intervention on behalf
of the Infantes de la Cerda and papal opposition to the
legitimation of his marriage and his children would be
eliminated. He also promised to give the Infantes joint
rule over Murcia and Ciudad Real as an independent
realm, provided they renounced all claims to Castile.
At that, Alfonso III of Aragón liberated the Infantes
and proclaimed Alfonso de la Cerda as king of Castile.
Inconclusive border warfare followed until 1291, when
the new king of Aragón, Jaime II, concerned about his
capacity to retain the kingdom of Sicily against papal
opposition, decided to make peace. Jaime II left the
Infantes de la Cerda to fend for themselves and agreed
with Sancho IV on zones of future exploitation and
conquest in North Africa.
The conclusion of this treaty came at an opportune
moment because the Merinids were preparing to resume
hostilities as soon as the truce with Castile ran out.
Although Benedetto Zaccaria, again in Castilian ser-
vice, defeated the Moroccan fl eet in August 1291, Abu ̄
Ya ’ q u ̄ b, the Merinid emir, invaded Spain soon after. In
the spring of 1292, Sancho IV, aided by Muh.ammad II
of Granada (who feared the Merinids), besieged Tarifa,
a port often used by Moroccan forces entering Spain.
Sancho IV entered the town in triumph on 13 October- The king of Granada, who had expected that Tarifa
would be restored to him, now broke with Castile and
SANCHO III, KING OF NAVARRE