Peter III of Aragon was a king who ruled from 1276 until his death in 1285. He was born in 1239 and was a member of the House of Barcelona. Peter is known for his efforts to expand the Crown of Aragon and for his involvement in the War of the Sicilian Vespers, which was a conflict over the control of Sicily. During his reign, Peter III strengthened the kingdom's influence in the Mediterranean region. He was also notable for his marriage to Constance of Sicily, which helped to solidify alliances and enhance the power of the Aragonese crown. His legacy includes the continued growth of Aragonese territories.