Answer: It helped them use the land they've known, either by hiding or launching clever attacks, against the British.
Explaination: The Americans knew the land they lived in. They knew were things were, which hiding spots were the best, and where the British might come. Now, this factor may not have been the most effective during the Revolutionary War, but it certainly was a big help. The British just came and attacked, but the Americans knew when to pop out of the bushes or when to be at a specific area.
In these ways, geography was useful to the Americans.
