I Tamed a Tyrant and Ran Away is a Manga/Manhwa/Manhua in english language, Drama series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.nl fastest updating comic site. The Summary is

God gave me a chance to relive my life. Before the rebirth, I had been used for the past 400 years as the empire's sword. And so, I swore to destroy the empire. I found the young prince of the country and became his teacher. I taught him how to become a tyrant and asked for the country.

"I will do the lady's will."

He conquered the whole empire for me, and I ran away.