Start talking about hold-ups at cross-roads that are clear. Tell them about shortcuts that actually lead through marshes. Tell them "the attack we discussed earlier will actually happen 43 minutes earlier". Tell them, "hey we have run out of food here". Tell them, I heard that 10 miles back they are serving hot food, damn I wish I was there.

Just fuck with their comms, making them either make wrong decisions, demoralize them, or make them abandon these comms for something even worse.