What is Charlemagne greatest accomplishment?

Charlemagne's greatest accomplishment is often considered to be his role in uniting much of Western Europe during the early Middle Ages, effectively laying the foundations for modern France and Germany. He expanded the Frankish empire through military conquests and strategic alliances, promoting cultural and educational reforms known as the Carolingian Renaissance. His coronation as Emperor of the Romans in 800 AD by Pope Leo III symbolized the fusion of Roman, Christian, and Germanic traditions, influencing the political landscape of Europe for centuries.