Fort Wentworth in the southwestern New Hampshire town Northumberland is located at the junction of what two rivers?
Fort Wentworth:  The fort was built at the junction of the Upper Ammonoosuc River and Connecticut River, in Northumberland, New Hampshire, by soldiers of Colonel Joseph Blanchard's New Hampshire Provincial Regiment including Robert Rogers. Northumberland, New Hampshire: Northumberland is a town located in southwestern Coos County, New Hampshire, U.S., north of Lancaster.
Upper Ammonoosuc River and Connecticut River