In 405 AD, the Ostrogoths invaded Italy itself, but were defeated. However, in 406 AD an unprecedented number of tribes took advantage of the freezing of the Rhine to cross "en masse": Vandals, Suevi, Alans and Burgundians swept across the river and met little resistance in the Sack of Moguntiacum and the Sack of Treviri, completely overrunning Gaul. Despite this grave danger, or perhaps because of it, the Roman army continued to be wracked by usurpation, in one of which Stilicho, Rome's foremost defender of the period, was put to death.