Why were Roman Legions recalled to Rome?

Rome recalled the legions towards the end of its power. Rome was crumbling from within, and was in open civil war. There was economic trouble, domestic dissent of a revolutionary nature, and a series of weak and unpopular leaders who were unable to reverse Rome's decline. The Legions were recalled from all the corners of the empire, in an attempt to stem the tide. Unfortunately, since Rome's population had also been in decline for generations, many of the soldiers that came back were German mercenaries, who sacked and burned Rome in 455 AD.