John I, Duke of Alençon was a French nobleman born in 1404. He was the son of Charles, Duke of Alençon and Marie of France. John became Duke of Alençon in 1415 and was known for his military involvement during the Hundred Years' War between England and France. John I played a significant role in various battles, including the defense of Orléans. He was a supporter of Joan of Arc and participated in the campaign to lift the siege of the city in 1429. John I died in 1434, leaving a legacy as a dedicated military leader.