Helsreach

Helsreach - Aaron Dembski-Bowden Dark, gothic sci fi in the world of Warhammer 40,000.
Grimaldus becomes the Reclusiarch of the Black Templars, only to be left with a token force in Hive Helsreach as it undergoes a massive Ork invasion.

The author does a good job of using the inhumanity of both the Orks and Space Marines to bring out the natural qualities of the supporting characters who inhabit the world.

Lots of battles, good characterization.

The only thing that detracts through the story is that it sometimes tells the story in first person from the viewpoint of Grimaldus, and then switches into third person to go and explain another part of the battles.