John III, Duke of Jülich-Cleves-Berg was a nobleman who ruled from 1521 until his death in 1539. He was born in 1490 and was part of the House of La Marck, a prominent family in the region. His reign was marked by efforts to strengthen his territories and maintain their independence amidst the political complexities of the Holy Roman Empire. During his rule, John III faced challenges from neighboring powers and worked to secure alliances. He was known for his diplomatic skills and sought to enhance the economic stability of his duchy. His legacy includes the promotion of trade and the arts in Jülich-Cleves-Berg.