Well, Germanicus the older or Germanicus the younger? I've just read a very interesting book on the Varus battle and the surrounding campaigns.

From what I know, Germanicus the younger suffered casualties when he had to storm the castrum of a mutinous legion where several thousand were killed. Second, after having campaigned against the Cherusci and won the "great" battles of Idistaviso and at the Angrivarierwall, his fleet was surprised by a storm on the way back home along the Frisian coast, where thousands of legionnaires drowned.