John I of Cleves was a nobleman from the House of La Marck, born in 1417. He became the Duke of Cleves in 1448 and ruled until his death in 1481. His reign was marked by efforts to strengthen his territory and maintain its independence amid the political complexities of the Holy Roman Empire. John I was known for his diplomatic skills, often engaging in alliances through marriage. He was the father of Anne of Cleves, who later became the fourth wife of King Henry VIII of England. His legacy includes the promotion of trade and culture in his duchy, contributing to its development during the late Middle Ages.