Born in Toledo, Spain, Alfonso was the eldest son of Ferdinand III of Castile and Elisabeth of Hohenstaufen, known in Spain as Beatriz de Suabia, through whom he was a cousin of Frederick II, Holy Roman Emperor. In the period 1240??250 he conquered several Muslim strongholds in Al-Andalus alongside his father, such as Murcia, Alicante and Cadiz. In the siege of Niebla (1262) he used cannon to defeat the Muslim defenders. This is the first recorded use of gunpowder for military purposes by Europeans - ironically a technqiue learned from his Muslim opponents.