King Peter III of Aragon, also known as Peter the Great, ruled from 1276 to 1285. He was a member of the House of Aragon and is best known for his military campaigns against the Kingdom of Castile and his efforts to expand Aragon's influence in the Mediterranean. His reign marked a significant period of territorial growth for the kingdom. Peter III was also notable for his marriage to Constance of Sicily, which strengthened ties between Aragon and Sicily. His rule was characterized by a focus on consolidating power and promoting trade, contributing to the prosperity of the Crown of Aragon.