Explanation: One of the early excuses for Caesar's incursion into Gaul was that several Gallic tribes requested his help in expelling a Germanic invader by the name of Ariovistus. Caesar would expel Ariovistus, and then go on to 'overstay' his welcome amongst the Gallic tribes, putting Gaul under effective Roman domination.
... for bonus points, Ariovistus was, himself, invited in by Gallic tribes who needed help against their enemies, and then overstayed his welcome in subduing the locals to effective Germanic vassalage.
One thinks that Gallic politics might've been a bit self-defeating...