The battle between the Remnant Forces and the Elysian crusaders, while bloody for both sides, was short-lived. Ultimately, the objective of the Marines was successful. Eliminate Elysian means of production via precise artillery strikes. And cause chaos among the population.
If they had wanted to completely obliterate Elysium, then they would have brought an actual brigade worth of troops. Such a thing was unnecessary for the time being. Still, the Elysian Crusaders caught up to them quicker than anticipated.
And the losses sustained in combat were far greater than anyone in the Remnant had calculated. Of the roughly 500 Marines sent to Elysium, less than a hundred of them successfully withdrew from the Elysian Pursuit. All others were either killed in action, or were captured by the Cultists.