Charlemagne killed people that wouldn't convert to Christianity . He also killed Muslim that invaded his empire trying to convert everyone by force. His grandfather was dedicated his life to it. In addition , Charlemagne wanted to unite all tribes into one. This was very important because this showed people not to mess with him because he killed so many people in the river that it turned red.
The Frankish king devote his life to Christianity if the Clovis army won which was unlikely but the did. The Clovis army of 3000 defeated them which was surprising. They were all baptized by a catholic bishop. Then another army known as the Muslim invaded the Pyrenees Mountains in 732 and they won.
The reason Charlemagne was given the name great was because he improved the kingdoms economy by standardizing weight and minted a silver coin. He continued to prove this was by being organized.
If you were a peasant and accused of a crime the only was to prove your innocence was to hold a hot red poker until your hand was deeply burned. If your hand healed in 3 days you were innocent ( which was not likely to happen ) if it didn't you were guilty. If you were a Nobel you had to fight or pay someone to fight for you . You win you were innocent. Charles created a system that had a Honorable man listen and use real evidence which we use till this day.
He wanted people to be able to read and type because he thought it was important so just in case he sends directions to something they can read it so it makes its easier on him. So he doesn't have to travel everywhere which he still did anyways but it will save him a lot of time. He starts turned his place into a learning center and hired people to teach. All in all this helped people convert to Christianity because they needed to know how to write and read.
Charlemagne ordered his scholars to write everything down because he wanted to preserve knowledge for the next generation to know and pass down. This was smart of him to do because it showed that he wanted to make every one know how to do things.