In the 1820s the border dispute between Canada and Maine that became known as the "Aroostook War" prompted the United States to send troops to northern Maine.

The dispute concerned a tract of land that stretched north from Mars Hill to near the Saint Lawrence River and arose from ambiguous language in the Treaty of Paris of 1783 that ended the American Revolution.

Hancock Barracks was built to support the troops assigned to protect U.S. interests throughout the region.