Succesful surprise attacks tend to lead to decimated armies at the best of times, so eh... The degree to which he "united the Germans" is kinda questionable though, as he'd just managed to gain the following of a handful of tribes; IIRC he spent the next quite a while warring with other chieftains and wannabe kings...
Very true, and then there's the fact that he ended up being assassinated by his own people. -M