User blog comment:Th3Gh0stWr1ter/Essay: The Eras of Redwall (1986-2011)/@comment-26538658-20160310013858/@comment-4983187-20160311072617

I can definitely see there being less of a "liberation of foreign lands" narrative in the later books, which seem to feature villains who are explicitly out to get the story's protagonists.

Not sure if I agree with you entirely on the lack of happy endings. Every story ends with the main villains being killed. Doomwyte in particular also ends up with a huge amount of married couples, including an Abbess, which is unprecedented in Redwall history.