The most important way in which the ways of the Germanic people influenced European civilization was through their impact on the system of feudalism. The rules of feudalism came to Europe from Germanic traditions and laws.
In the Germanic societies, there had been a form of bond between leader and followers that became the backbone of feudal society. This bond came to be known as vassalage. In this system, men swore loyalty to a leader. They swore to fight for him when he needed them. In turn, the leader swore to protect the men who were his vassals. The chief virtue of a German vassal was his allegiance to his lord.
These same things came to typify feudalism. Feudal society was marked by lord-vassal relationships in which loyalty to one's lord was of utmost importance. This idea, derived from Germanic society, shaped European civilization for much of the Middle Ages and even beyond.