600-100 BC: Although Germanic peoples were first mentioned in writing some six hundred years before the common era, they did not "officially" burst into the Mediterranean world until the second century BC with the invasion of Italy by the Cimbri and the Teutons, who were finally routed by the Romans in 101 BC.

58-51 BC: Caesar decides to invade Transalpine Gaul in 58 BC when protests by various Gallic tribes in loose confederation with Rome arise against the Suevi, a German tribe that had recently conquered territory in Gaul, and when he hears reports of a threatened invasion by the Helvetii, a Celtic tribe from the area that is now in Switzerland. Not only does he force the Helvetii to withdraw, but he also kills the Suevi's leader, Ariovistus, in Alsace after an arduous offensive. Over the course of the various campaigns that constitute the "Gallic...