This is my understanding. Most of what I've read suggests that there was lots of "tribal raiding" going on, but "warfare" pretty much by definition requires larger polities such as city states or nations which are thought to be a more recent development.

I don't know about Germany, but the UK is full of ancient fortifications - from earthworks that would enclose a few huts to huge ruined stone fortresses. Almost all of these get very little attention.

I thought most of these fortifications are thought to be bronze age, not neolithic.

In fact they are probably later, but they are definitely "prehistoric" in the sense that for most (certainly here in Scotland) there are no records, written or oral, for most.