Respuesta :

Charlemagne's greatest achievement was conquering much of Europe. He stability to a large area during an unstable time in history. 
✡ Answer: Gaining power to most of Europe. ✡

- - Why? 
This was Charlemagne's greatest victory and achievement, the one he feels like was best. The one he tried hardest to do.

✡Hope this helps✡

Q&A Education