In 9 A.D., the Emperor Augustus sent P. Quinctilius Varus to conquer Germany and push the eastern boundary of the Roman Empire as far as the Elbe River. Varus' legions were annihilated in the battle of Teutoburg Forest. Another unsuccessful invasion was attempted under Caligula in 39 A.D. After that, the Romans satisfied themselves to remain behind the line of fortifications they had built in Vindelicia and along the Rhine River. In the second century A.D., confederations of Franks, Alamanni, and Burgundians attempted to cross the Rhine, but were defeated by the Romans.
In the fourth and fifth centuries A.D., the Huns pushed westward from Asia, forcing Germanic tribes to seek new territory in the lands controlled by Rome. By this time, the Empire had been so weakened by internal strife it was incapable of resisting the waves of Ostrogoths, Visigoths, Franks, Vandals, Lombards and other tribes moving across their borders.
By the end of the fifth century, Britannia had been occupied by the Angles and Saxons, Gaul by the Franks, Spain by the Visigoths, North Africa by the Vandals, and Italy by the Ostrogoths, and the Western Roman Empire had been destroyed.