Ordoño III, like his father Ramiro II, had to face Abderramán III, since this Muslim Sovereign had a long life and governed al-Ándalus for almost fifty years. There were almost yearly battles between Ordoño and Abderramán. Muslim historians recounted that Abderramán won all of the battles, while the Leonese only spoke of Ordoños victories. Neither are completely in the right: one of the main duties of current historians is comparing both versions of a story to attempt to reconstruct a reality.
Ordoño had to suppress several rebellions over the course of his reign. One of them was directed by his own brother Sancho, who received the help of the kingdom of Pamplona and Fernán González, the Castilian Count. In spite of this, Ordoño won against them, and Sancho had to flee the kingdom. One of his biggest triumphs was looting the distant and muslim area of Lisbon. During the last years of his reign, he signed a truce with Abderramán III, which brought some peace to the Leonese kingdom.
A historian from the time mentioned Ordoño was prudent, and a great military strategist. Ordoño III passed away in Zamora around September of 956. He had a son named Bermudo, who would only reign later on (984-999), because Ordoño was succeeded not by his son, but his treacherous brother, Sancho.