Pedro Fernandez de Castro was Lord (Señor) of Lemos and Sarria and served as mayordomo mayor (lord steward) of Alfonso XI of Castile, adelantado de la frontera (governor) of Andalusia, Galicia and Murcia and pertiguero mayor (a title similar to the French Vidame) of the lands of Santiago.

Around the year 1319, Pedro Fernandez de Castro returned to Galicia and Alfonso XI of Castile gave him his ancestral manor of Lemos and Sarria and appointed him Lord Steward of the realm.

In 1330, Pedro accompanied King Alfonso on his campaign into Granada and led the Christian attack at the Battle of Teba In 1334, Afonso IV of Portugal invaded the kingdom of Castile and León, entering through the lands of Galicia.

Due to his military skills, Alfonso XI sent Pedro Fernandez to fight Muslims in Andalusia, where he fought at the Battle of Salado in 1340, where tradition refers to Pedro Fernandez de Castro grabbed his spurs of gold from the Marinid sultan of Morocco, Abu Al-Hasan Ali ibn Othman.

During 19th century his tomb was examined and found next to his remains were some pieces of silk, a brooch and gold spurs, which are supposedly those of Sultan of Morocco Abu Al-Hasan Ali ibn Othman, of which Pedro Fernandez de Castro had seized during the Battle of Salado.