I haven't read the C.S. Forester book so I don't know if this was in it but why in the world would the Germans have built a fort to control a river that was impassable in both directions by raging rapids? They could not have hauled the materials to build it or supply it by the river.
shareAnd that's what the German's wanted you to think.
It could have been a monastery, or built for some other use.
Also, Charlie and Rose and talked about going past it at night. Why didn't they?
shareRose suggests they go past the fort at night but Charlie tells her that the rapids are just downriver feom the fort and it would be too dangerous to shoot the rapids in the dark. She then suggests that they stick to the far side of the river when they pass.
shareThey explained in the dialogue that the Germans were going from village to village burning, killing, and rounding up soldiers. Presumably they took control of an old fort,church or some other stone building as a base from which to go out and sack villages. I never got the sense that they built that.
As for passing by at night, Charlie explains that the rapids would smash them to bits.