 Presumably, the Quadi wished to avoid trouble themselves by allowing these tribes to pass through into Roman territory.This invasion was apparently thrown back into Quadi territory without too much difficulty as far as the Romans were concerned, but the incursion marked the start of a long series of attempts to cross the border.A few years later, the Marcomanni and Quadi, with assistance from other tribes that had crossed the Danube, overwhelmed a Roman army, passed over the plain at the head of the Adriatic, and put the town of Aquileia in northern Italy under siege.