The Seventh Retro War or Seventh Time Assault was a morally-questionable series of manoeuvres on Earth inspired by Robert Scarratt's apportation tactics. They were designed to cloud all ongoing House Military operations through "atavistic camoflage". During the Assault, the Seventh Wave demonstrated their ability to psychologically violate and degrade civilian populations.
Ultimately, the Assault was interrupted by the enemy, and the timeline was reordered into the Seventh Retro-War. (PROSE: The Book of the War)
The Celestis influenced the Seventh Retro War. When One was sent to clean up any loose ends caused by the Celesti operation, he let some pockets of resistance survive, causing the Eighth Retro War to be fought a millennium earlier. (PROSE: The Taking of Planet 5)