My stack in Annapolis was besieged for 6-7 turns. My military control of the region dropped to only 5 percent but even then I could destroy railroad in the region. Now the problem is there was no "Destroyed railroad" icon next turn popping up on the map. I repeated the process for 3-4 turns hoping to delay Union forces from Baltimore going to Washington, but the outcome was the same - no icon
P.S McDowell stack was sitting int he region all the time. Maybe the icon was beneath him? Or maybe his force was repairing the railroad very fast? Or maybe you cannot destroy railroads when besieged?
P.S Playing 1.02 demo.