Based on a book that's at least partly based on reality, it tells of Operation Market Garden: In 1944, British, American, and Polish forces plan to use paratroopers and tanks to capture numerous bridges in the occupied Netherlands. Many soldiers doubt the feasibility of the mission, as it involves considerable travel along narrow roads, there's fog to consider, and even if the Germans don't send their best, they won't be pushovers. If you know this chapter of history, you know the doubts are correct.