Scar Night by Alan Campbell

550 pages long.

Pollution; an ancient, crumbling civilisation, steeped in religion; great machines; the lower people scrounging to survive while loftier, governing people have easier lives, all this and a supernatural menace... The Deepgate Codex series begins!

A Bolo Novel by John Ringo and Linda Evans

The story of an out of date - surplus to requirements, self aware, robotic tank and its commander posted on a distant world in huma space to act as protector of the plant from alien invasion's.  They are caught up in the political and civil conflicts that ensue after an unsuccessful invasion by the Deng, thwarted by the Bolo.   The Bolo finds itself in uncharted territory, commanderless and following the orders of fanatical and dubious leaders.