I recently read a book called "Redliners" by David Drake about a platoon of soldiers trying
to escourt a group of settlers to their soon to be buil colony on a hostile alien world. The catch
is that the world is alive but also built by aliens. The human race is also in a stalemated war
against a third alien agency who also is on the planet., trying to "unlcok it's secrets".
"Redliners" is extremely gritty and not for the sqeamish.
Also "Voice of the Whirlwind" by Waler Jon Williams takes place in a world integrated with
the aliens after an artifact war(over their artifacts) amongt the human factions leaves
millions dead.
Good stuff.