The Aroostook War was an undeclared and largely bloodless boundary crisis between Maine and the British colony of New Brunswick. Its roots lay in ambiguous language and imperfect geography in the 1783 Treaty of Paris, which left roughly 12,000 square miles claimed by both sides.

Main crisis1838–1839
LocationNortheastern Maine and New Brunswick
Central issueInternational boundary and timber claims
ResolutionWebster–Ashburton Treaty, 1842

Origins of the dispute

The treaty ending the Revolutionary War described a boundary using waterways and a “highlands” divide, but contemporary maps were inaccurate and the identity of the river intended as the St. Croix had been uncertain. The result was a large “Disputed Territory” vulnerable to competing jurisdiction and settlement claims.

After the War of 1812, Britain remained concerned about the overland communication route connecting Halifax and Quebec. Part of that strategic corridor crossed land claimed by the United States, raising the stakes of the unresolved boundary.

A broad northern river winding through forested terrain
Rivers, watersheds, forests, and incomplete maps were central to competing interpretations of the northeastern boundary.

Arrests and escalation

When John Baker accepted a land grant from Maine in the disputed region and asserted American authority, British officials arrested him. He was taken to Fredericton and convicted in 1828. That same year, the United States established a garrison at Houlton, while work began on the Kennebec Arsenal in Augusta.

The dispute intensified in 1837 after New Brunswick officials arrested a Maine land surveyor conducting a census in territory claimed by both jurisdictions. A related boundary map appears with the Webster–Ashburton Treaty entry.

Maine’s legislature authorized funds to defend its claim and supported a military road toward Houlton, approximately following the later route through Macwahoc. Another proposed road, later associated with the Airline, was intended to connect Bangor and Calais but was not completed at that time.

Why roads and forts mattered

The dispute unfolded in a remote, heavily forested region. Roads made it possible to move people and supplies, while fortifications signaled an intention to hold strategically important river corridors and frontier settlements.

Fortifications on the frontier

Fort Knox at Prospect was developed in response to concern that British ships might again threaten the Penobscot River. Farther north, near the disputed frontier, Fort Kent was built between 1838 and 1840.

Records concerning the Maine Military Road describe state militia work on a route to Haynesville from the Plummer–Prouty Turnpike. The surviving material includes construction contracts and a March 22, 1839 letter concerning a sutler for the Kennebec Division and construction of a frontier fort.

Historic timber blockhouse standing beside trees
Timber blockhouses represented the practical frontier architecture of the boundary crisis.

The crisis of 1839

An expedition of about 200 men led by state land agent Rufus McIntire detained several New Brunswick residents, including disputed-territory warden James McLaughlin. New Brunswick officials then arrested McIntire and other Maine volunteers.

Maine responded by appropriating $800,000 and authorizing a militia of 10,000 men. Congress subsequently authorized $10 million and empowered the federal government to raise 50,000 troops if required. Troops mobilized and defenses were prepared, but the two sides did not meet in a formal battle.

The episode is often called the nation’s only bloodless war. A frequently repeated story places its only physical clash in a Houlton barroom, where British and American soldiers reportedly exchanged blows after a provocative toast. Whatever the details of that encounter, the boundary crisis itself produced no battlefield deaths.

Diplomacy and the boundary settlement

Immediate hostilities were avoided through a temporary agreement that reduced military tension. The larger dispute remained until U.S. Secretary of State Daniel Webster and British diplomat Alexander Baring, Lord Ashburton, negotiated a permanent settlement.

The resulting Webster–Ashburton Treaty of 1842 established Maine’s present northeastern boundary. It divided the disputed territory while protecting Britain’s desired communication corridor and clarifying American jurisdiction over much of the region claimed by Maine.

Additional resources

  • Aroostook War: Historical Sketch and Roster of Commissioned Officers and Enlisted Men Called into Service for the Protection of the Northeastern Frontier of Maine, from February to May, 1839. Augusta: Kennebec Journal Print, 1904.
  • Burrage, Henry S. Maine in the Northeastern Boundary Controversy. Portland: Printed for the State, 1919.
  • Campbell, W. E. The Aroostook War of 1839. Fredericton: Goose Lane Editions, 2013.
  • Correspondence and Documents Relative to the North Eastern Boundary, 1825–1840.
  • Documents Relating to the Disputed Territory. Maine Legislature, House, 19th Legislature, 1839.
  • Gallatin, Albert. A Memoir on the North-Eastern Boundary: In Connexion with Mr. Jay’s Map. New York, 1843.
  • The Maine Military Road, 1830–1839.
  • Merk, Frederick. Fruits of Propaganda in the Tyler Administration. Cambridge: Harvard University Press, 1971.
  • Sprague, John Francis. The North Eastern Boundary Controversy and the Aroostook War. Dover, Maine: Observer Press, circa 1910.
  • Stadig, Rita B. Aroostook War: The Little Lake Fort Is Located. Soldier Pond, Maine, 1994.