And since they were fully armed and in military uniform, I have to believe there is still a military compound somewhere within maybe a hundred miles.......
I wonder if they will figure in to any future episodes...........
If you recall, a helicopter from that base crashed in that episode or the one before and a survivor said that the base had effectively fallen.
That’s how the governor knew to expect the small convoy. Its been months but I think the helicopter was scouting a path for the guys traveling by road.
As cripplecreek said, the small military unit was basically a group of refugees from Fort Benning, GA, which had been overrun by walkers.
http://walkingdead.wikia.com/wiki/Lieutenant_Welles
Well they explain in that very episode the Soldiers in the helicopter were scouting for the convoy that the Gov. goes back and ambushes. The soldier they rescue from the helicopter said their army base got over run by walkers and their convoy was all that survived.