Question

Which weakened the defense of the Roman Empire's northern frontier?

Answer 1

The defense of the Roman Empire's northern frontier was weakened by the invasion of barbarian tribes who bypassed Roman defenses. The underfunding and understaffing of Roman armies in the west also contributed to the weakened defense.

Step-by-step explanation:

The defense of the Roman Empire's northern frontier was weakened by several factors. One major factor was the invasion of barbarian tribes who took advantage of the frozen Rhine river in 406 CE to bypass Roman defenses. The Vandals, for example, sacked Roman provinces in Spain and seized territory there. Another factor was the underfunding and understaffing of Roman armies in the west, which led to poor military performance and the loss of territories.