The tree roots of medieval culture in Western Europe are The classical heritage of Rome, the customs of various Germanic tribes and the belief of the Roman Catholic Church.
The reason Charles Martel’s victory was so important for Christianity is because the victory at the Battle of Tours prevented Islam from spreading into Europe. This preserved Christianity for a long time due to the fact that if the Muslims had won, Western Europe would most likely have been part of the Muslim empire.
Charlemagne’s greatest achievement was in 800 when Charlemagne went to Rome to defeat a mob that attacked the pope. It was a very historical event when Pope Leo 111 crowned him as the emperor giving the title Roman emperor to Charlemagne. They joined the Germanic power, the church and the heritage of Roman Empire.