House of Lara
Lope Díaz came to power in difficult times after the death of his father on 16 October 1214. A few days after he came to power, King Alfonso VIII of Castile died, leaving his 10-year-old son, the ill-fated Henry I of Castile, as heir to the throne after mysterious the death of his older brother, Fernando de Castilla y Plantagenet. The House of Lara gained power over Henry and started a rivalry with his sister, Berengaria of Castile, who consequently was Lope Díaz' patron. In 1217, Henry was 'accidentally' killed at the age of 13 by a falling roof tile. He was succeeded by his sister Berengaria, with the support of Lope Díaz, amongst other nobles, who later abdicated in favor of her son Ferdinand III of Castile, crowned in Nájera. Alfonso IX of León, the father of Ferdinand III was against the coronation of his son and invaded Castile with the support of the House of Lara. During this invasion, Álvaro Núñez de Lara gained power in Nájera and was subsequently defeated and imprisoned by Lope Díaz.