<P> In the late 4th century, the empire was controlled by members of a dynasty that included the Emperor Theodosius I . This family retained political power within itself and formed alliances by intermarriage with other dynasties, at the same time engaging in internecine power struggles and fighting off outside contenders (called "usurpers") attempting to replace the ruling dynasty with one of their own . These internal machinations drained the Empire of both military and civilian resources . Many thousands of soldiers were lost in battling attempted coups by figures such as Firmus, Magnus Maximus and Eugenius . </P> <P> The Empire's historical relationship with Germanic tribes was sometimes hostile, at other times cooperative, but ultimately fatal, as it was unable to prevent those tribes from assuming a dominant role in the relationship . By the early 5th century, as a result of severe losses and depleted tax income, the Western Roman Empire's military forces were dominated by Germanic troops, and Romanised Germans played a significant role in the empire's internal politics . Various Germanic and other tribes beyond the frontiers were able to take advantage of the Empire's weakened state, both to expand into Roman territory and, in some cases, to move their entire populations into lands once considered exclusively Roman, culminating in various successful migrations from 406 onwards . The crossing of the Rhine caused intense fear in Britannia, prone as it was to being cut off from the Empire by raids on the primary communications route from Italy, to Trier to the Channel Coast . In the event, this was much more than just another raid . </P> <P> In 383, the Roman general then assigned to Britain, Magnus Maximus, launched his successful bid for imperial power, crossing to Gaul with his troops . He killed the Western Roman Emperor Gratian and ruled Gaul and Britain as Augustus (i.e., as a "sub-emperor" under Theodosius I). 383 is the last date for any evidence of a Roman presence in the north and west of Britain, perhaps excepting troop assignments at the tower on Holyhead Mountain in Anglesey and at western coastal posts such as Lancaster . These outposts may have lasted into the 390s, but they were a very minor presence, intended primarily to stop attacks and settlement by groups from Ireland . </P> <P> Coins dated later than 383 have been excavated along Hadrian's Wall, suggesting that troops were not stripped from it, as once thought or, if they were, they were quickly returned as soon as Maximus had won his victory in Gaul . In the De Excidio et Conquestu Britanniae, written c. 540, Gildas attributed an exodus of troops and senior administrators from Britain to Maximus, saying that he left not only with all of its troops, but also with all of its armed bands, governors, and the flower of its youth, never to return . </P>

Who got rid of the romans in britain