So i'm starting to put pieces together in my head to establish a proper universe of my own, right now i'm just calling it Tin Soldiers because it's a term that just sort of stuck.
Earth federation forces stay behind to give civilian transports a chance to make orbit during the fall of New Marathon. The defenders rally around elite M.A.R.S units dropped directly from orbit into the front line as their vessels engage the enemy in orbit. The EFS Icarus and it's battle group float directly above the city providing desperate air cover for the remaining evacuation areas as humanity abandons it's last bastion on mars.
Credit to phelandavion.deviantart.com/
for one of his stocks!