I say start earlier . . .
Just to sort of see what it was like to start on Gray Monday. You can make a pretty interesting story about why they became mercenaries and how they got their gear- my set were a mixed company were test pilots for a refurb yard. They started with a few machines that were being repaired, a stockpile of parts, but very little ammo. Sitting on the stockpile of parts for the company & RAF made them a target for everyone. Then dealing with the emergency becoming a permanent thing, wannabe warlords, political power grabs, cameos by Dragon's Fury, Bannson's rep trying to get cozy with local pols, evacing with the proto-Stormhammers, and trying to get to Galatea as the 'merc' world.
For this you would IMO need the Historical Dark Ages PDF, but there are some other sources of information like TP Irian.
The appeal for me was that you had a LOT of little factions running about shooting at each other so you could always find someone who needed more guns.
Empyrus is referring to the Galatean League or whatever they call themselves . . . they are basically live fire training for the Crusader Wolves as time goes on- think Coventry defenders in '58 but over the span of years. Early on they might have been defending a collection of worlds from the Falcons & Wolves . . . but the Falcon Desant was not dishonorable or vindictive under Helmer like when Mad Malvina was running the show. Unfortunately, she makes some sort of link up with the Desant going into 3145 (see latest Battle of Hesperus) and so pushing back in that direction gets more dangerous than it was in the late 30s. Alaric has been slowly nibbling away by sending his new formations against the mercenaries that are defending the League and Republic Remnant based on Callison, I think as their worlds have shrunk in the 3140s that you might have had mercs that were strong early backers sliding off to somewhere else.