It has me thinking of a stranded fleet with refugee ships who get stranded in some out of the way binary system. Both stars have inhabitable planets in their own life zones. the fleet takes over a couple of planets orbiting the "A" star, the "B" star is ignored for now. 

Military rule is established with mandatory compulsory service, some manufacturing is set up with restrictions on what can be produced, the priority being keeping the fleet on a battle footing. Eventually, they decide to split the fleet, one have protecting the civilians, the other half trying to find a way out.

While they've not returned in the last two or three hundred years, intelligent life has been discovered orbiting the B star - and they're not happy about the humans. I should say I'm rather new at this.