Federal Old Battle Ships are large warships originally manufactured by the Ades Federation. Since their production, as Ades has replaced its part of its fleets with more modern Ades Battle Ships, and many Federal Old Battle Ships still in active use belong to other nations which purchased them as military surplus. For instance, the fleet of Notos is composed of Federal Old Battle Ships.
It should be noted with humor, perhaps the reason these old ships were put out of use was because of the very flaw used by Fam and Millia to sink it the Anshar, which is an upgraded Federal Old Battle Ship. One single projectile from the flare gun was enough to bring the ship down.