Board Thread:Warhammer 40k General Discussion/@comment-25222488-20151025234507/@comment-25507520-20151106135517

It was just speculation, we know it wont happen.

However, no, all the Space Marine Chapters in the galaxy couldn't fight off the bigger hive fleets, heck, if Hive Fleet Leviathan wins the Octavian War (which they probably will...) then that Hive Fleet alone might decimate the galaxy.