Fort Wentworth was built by order of Benning Wentworth in 1755. 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. In 1759, Rogers' Rangers returned here hoping for resupply after their raid on St. Francis, Quebec, but the fort had no garrison and no supplies. Rogers had to travel down the Connecticut River to Fort at Number 4 for reinforcements and supplies for his hungry men.