I'm thinking about the 14th year war, FS1, here. I suppose a single fleet (or battle group), always had only one Orion-class destroyer. It would seem to be logical, as "the cost to build one of these far outweighs the cost of paying the crew of this ship for 3 years". So, looking up at the briefings and tech room descriptions, I've so far found out this:
GTD Amadeus was the flagship of the 3rd fleet, until being destroyed in 1/25/35 by the Shivans in the Vega system.
GTD Bastion is the flagship of the 5th fleet, as the briefing for the mission Hammer and the Anvil states that "A strike squad sent from the 5th fleet was able to recover some Shivan shield prototypes". This is an obvious reference to the previous mission.
GTD Eisenhower was the flagship of the 4th fleet, before being destroyed by a PVD Typhon in the Vega system on or about 2333 (tech room "...in the two years since this ship first appeared..."). In fact the whole 4th fleet was destroyed, which raises the question, was this fleet ever re-formed, or did they simply create a new fleet to replace the destroyed one.
That leaves us the GTD Galatea, GTD Intrepid and the GTD Minnow with no fleet assignment mentioned (as far as I remember, correct if I am wrong). From the ref bible: "There is no more important symbol of Terran Pride than a ship like the Galatea or the Intrepid cruising past a colonized planet, patrolling the system and ensuring safety." So obviously both of these ships are top-of-the-line, and would propably be stationed in a more important fleet, such as the 1st (Sol?) or the 2nd. And what about Minnow? Unless they reformed the 4th fleet, propably the 6th. Pure speculation, this part, thought.
So...what are your thoughts?