Marathon or Halcyon Cruiser? Edit
It doesnt say if the cruiser in the battle group was a marathon or a halcyon cruiser so it could be either one. It might be a halcyon cruiser since it saids it in halo fall of reach that there are only 20 cruisers left in the fleet and 11 of them might be halcyon cruisers since 11 of them were brought back into service in 2550 and if any of them were not destroy until 2552 then there will be 9 marathon cruisers still in the fleet and 8 of them protected earth in the first battle of earth. So the only problem is where is the last marathon cruiser is it in the battle group or somewhere else or destroy.