The American's could keep an eye out for the British and prevent them from foraging into the countryside. This gave them an advantage over the British.
there’s not many, but I would say that nobody knew how far it was to get some help, (if you don’t know, valley forge was a camp during the American revolution that was really dangerous since it was during winter. Snow was heavy and there was no communication with the outside world)
also you could get lost in the mountains
