Let's read some Bede.
He was a Northumbrian monk, lived from 672/673 to 735. His relevant work to our topic is the Historia ecclesiatical gentis Anglorum. I just searched some keywords like "battle", "fought", "fled" or "slain" and gathered the parts which at least have some less generic and more detailed descriptions of battles. Still, Bernd, don't expect much.
I used the copy of his book from Project Gutenberg Library btw.