Geoffrey Plantagenet was born in 1158 and was the son of Henry II of England and Eleanor of Aquitaine. He became the Duke of Brittany through his marriage to Constance of Brittany in 1181. Geoffrey played a significant role in the political landscape of medieval England and France, often navigating complex alliances. Geoffrey was known for his ambition and desire for power, which sometimes put him at odds with his brothers, including Richard the Lionheart and John Lackland. He died in 1186 during a tournament, leaving behind a legacy that influenced the future of the Plantagenet dynasty.