Lope Díaz III de Haro

Lope Díaz III de Haro (b. ? – d. June 8, 1288, Alfaro) was a Spanish noble and head of the House of Haro. He was the 8th Lord of Biscay, a post which he gained by hereditary means after the death of his father. He held that title from 1254 until his own death in 1288 where he died attempting to assassinate the King of Castile.

He was son of Diego López III de Haro and Constanza de Bearne. His maternal grandparents were the Vizconde Guillermo II de Bearne and his wife, Garsenda de Provenza. Her paternal grandparents were Lope Díaz II de Haro, also Lord of Biscay, and of Urraca Alfonso de León, the illegitimate daughter of King Alfonso IX of León. Lope was the oldest of 5 siblings which included Teresa de Haro, who merged the Haro family with the House of Lara, and Diego López V de Haro who died during the Siege of Algeciras in 1310.

Lope took possession of the title of Biscay while still a minor after the death of his father. Due to the unnatural way in which his father died and the fact that his father had actively supported the overthrow of Alfonso X of Castile and had sworn allegiance to the King of Navarre, Lope's tutors brought the boy to Estella-Lizarra where he too offered his services to the Navarese King.

After long, Lope was reconciled with Alfonso X who reinstated Lope as Lord of Haro, a privilege his father had lost the family. Lope entered the service of Fernando de la Cerda, the eldest son of King Alfonso X. Fernando however ended up dying in 1275, throwing into question his line of succession. Disputes arose between two of his sons; Alfonso de la Cerda and Sancho de la Cerda who began jockeying for power and influence to see who would gain power over the succession of the Castilian crown. Lope decided to throw his support behind Sancho which turned out to be a savvy move.

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