I don’t want to sound like I’m catching creeping Spenglerism, after all this is only a trial balloon albeit one with antecedents (see #5 on this generally horrifying list), but isn’t recruiting foreign legions said to be one of the (many) causes of the downfall of the Roman empire?
The introduction of barbarians into the Roman armies became every day more universal, more necessary, and more fatal . . . As they freely mingled with the subjects of the empire, they gradually learned to despise their manners and to imitate their arts. … and though most of them preferred the ties of allegiance to those of blood, they did not always avoid the guilt, or at least the suspicion, of holding a treasonable correspondence with the enemy, of inviting his invasion, or of sparing his retreat.
— Edward Gibbon, The Decline and Fall of the Roman Empire 397 (1776)
And, yes, the headline may be a cheap shot, since Caligula was part of the Western (Roman) empire, and I think in in the quote above Gibbon was writing about the Eastern (Byzantine) Empire. But “Who does that cast as Diocletian?”, or Theodosius I, Flavius Zeno or Justin II, would all be better questions, but wouldn’t have the same zing.
Whatever Gibbon meant, given the state of things inside the Beltway and outside our borders, it’s to the Byzantine and not the Roman Empire that we should be looking to for models. So here’s a nice academic parlor game: Which Byzantine Emperor does W most resemble?