A fully assimilated half-German (specifically Vandal) second-gen immigrant almost saved Rome, if not for an out-of-nowhere pain train capped off by the Senate engineering a coup running him & his entire family over between 406 and 408 - Flavius Stilicho. Another half-German (in that case probably Gothic) saved the Roman world from Attila the Hun himself on the Catalaunian Plains - Flavius Aetius. (His father was described as a general from the province of Scythia, today's Dobruja split between Romania & Bulgaria, but by the late 4th century when that father would've been around the province had already been lost to the Goths in all but name.)

I would love to meet whatever son of a modern Somali migrant and the clueless AWFL who shrieked for his every crime to be excused can even remotely measure up to those men's quality. I suspect, though, that I will be waiting a very, VERY long time for such a surprise. To say the least.