During the youth of Fernando IV de Castilla (1295–1301) Diego López' exact date of birth is unknown, but it most likely occurred sometime around the year 1250. In 1282, he married the infanta
Violant of Castile, daughter of King
Alfonso X of Castile. On 25 April 1295, after the death of King
Sancho IV of Castile (who the Haro family had fought to overthrow), Diego López took advantage of the instability in the court of the young King
Ferdinand IV of Castile and took power over the Lordship of
Biscay which rightfully belonged to his niece,
María II Díaz de Haro. The incessant fighting against the Castilian crown, led primarily by the following infantes;
John of Castile, an enemy of the Haro family who claimed the throne as the heir to his brother, Sancho IV of Castile, Infante
Henry of Castile, son of
Ferdinand III of Castile and uncle of the young king Ferdinand IV, who claimed guardianship over the king. This was exacerbated by the claims of the infantes of Cerda,
Ferdinand de la Cerda and
Alfonso de la Cerda, who were supported by France,
Aragón, and their grandmother, Queen
Violant of Aragon, widow of
Alfonso X of Castile. Still further, problems also arose with the
Kingdom of Aragon, Portugal, and France, who all tried to take advantage of the instability that plagued the contemporary
Kingdom of Castile. Finally, internal Castilian players such as Diego López V de Haro,
Nuño González de Lara, and
Juan Núñez II de Lara, amongst others, sowed confusion and anarchy throughout the kingdom. During the summer of 1295, after the
Cortes of Valladolid of the same year, Diego López was confirmed in his illegitimate possession of the Lordship over Biscay, turned over by the pretender to both Biscay and the Castilian throne, infante John of Castile. During this time, John also temporarily accepted Ferdinand IV as his sovereign and he regained his previous possessions and titles. Disease and generally poor conditions became so bad in the Christian camp that Ferdinand IV was forced to pawn the jewels and crowns of his wife,
Constance of Portugal to pay his soldiers and knights. A short time later, the troops of
Felipe de Castilla y Molina, brother of Ferdinand IV, arrived in the Christian camp accompanied by 400 knights and many footsoldiers under the command of the
Archbishop of Santiago de Compostela. Towards the end of 1309, Diego Lopez V became sick as the result of an attack of
gout, from which he would later die in Christian camp on the River
Andarax. After months of failed attempts to take the city, Ferdinand IV decided to negotiate a peace with the Kingdom of Granada who had sent their emissary to the camp. They reached a deal where Ferdinand would lift the siege in return for 50,000 gold pieces and the towns of Quesada and Bedmar. ==Death and legacy==