40k Campaign - The Thorn Sub-sector

We are starting a few Warhammer 40K campaigns in my local area and online very soon. One has actually kicked off on VASSAL already. I'll be playing in them all and as such I wanted to have a map that we could use to track where the action is taking place. Its always nice to have a setting for the battles we fight on the tabletop. The overall campaigns won't really be linked but they can at least all take place in the same area and from that we can start filling in some details on that area. This might mean it comes to life and gets us more enthusiastic about playing or well it can just be an interesting read for the players if they want to come back and check out what we did. Anyway this location will be the Thorn Sub-Sector. I placed this on the fringes of the Imperium where anything we do won't really be effected by anything else that happens in the fluff. As we will have a heavy Ultramarine participation it would be best close enough to Ultramar, at least the marines won't have to travel far to fight. I shall be playing an Inquisitorial force that mainly consists of a homebrew Space Marine Chapter: the Sanctifiers. At the start of the year I painted some Ultramarines but as a friend already has them I instead modified them to have white arms and shoulders. A sufficent change to make them distinct but identifiable.