The Collapse of the Roman Empire--Military Aspects
             Modern historians explain the collapse of the western Roman empire in the fourth and fifth centuries in one of two ways. One group follows an institutional approach, which finds the reasons in the long-term and looks closely at internal structures. A second group has adopted a political approach and looks at short term causes of collapse.
             The long-term approach is the more traditional of the two. This argument suggests that Diocletian (284-305) and Constantine I (305-337) sowed the seeds of collapse. These emperors split the army into border and mobile components. The border troops became soldier-farmers and declined rapidly in efficiency, though they were still paid. Diocletian and Constantine also allowed many barbarians into the army, which had the result of decreasing its fighting efficiency. These historians argue that the weakness of the border troops meant that emperors needed more mobile troops, so they expanded the army. This in turn increased the number of recruits needed, while a simultaneous reluctance of landowners to lose scarce workers led to the recruitment of the militarily inferior barbarians.
             External problems exacerbated the internal crises of the empire. The small barbarian tribes who had opposed the early empire now banded together to form more powerful confederations such as Goths, Franks and Alamanni. However, some historians are doubtful about the increased power of these groups. Vigorous emperors like Diocletian, Constantine, Constantius II (337-361) and Valentinian I (364-375) kept the barbarians beyond the borders. Then the Huns arrived and drove the Goths into the Empire, defeating the army of Valens (364-378) at Adrianople in 378. From now on, the Romans could not destroy these Goths, although Theodosius I (379-395) finally settled them in the Balkans in 382. Once one group of barbarians had entered the Empire, the Romans could not muster the
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