User blog comment:WhiteSeraph/Alternate Timeline Idea That I'm Really Psyched About/@comment-3341288-20110927002311/@comment-25033299-20110927030855

Maybe Adeptus Phalanx? They could have defense-specialized power armor too... More ideas :D

As for the line, you pretty much nailed it. Giant space stations, booby-trapped worlds, planets with giant cannons, blockade after blockade, Craftworlds mixed in... There are hundreds of possibilities.