The storied gun battery known as Fort Blunder offers a lesson for civil engineers: Before you build, make sure your surveyors know what they’re doing.

In 1818, work began on a modern, heavy fortification built at the northern end of Lake Champlain. The British had launched massive invasions of the United States through the lake during the American Revolution and the War of 1812. As a result, some of the hottest fighting took place in the region during both wars.

Jim Millard in the America’s Historic Lakes blog writes,

Repeatedly mighty armies and massive naval flotillas had traversed the narrow reaches of the river between what is now known as New York and Vermont. The small islands to the north, Hospital Island, Ash Island, Isle aux Noix, had been the scene of frantic military activity and unspeakable suffering as these powerful forces drove north and south along the river.

To prevent that from happening again, President James Madison ordered the fort built. The State of New York helped out by ceding to the federal government a tiny spit of land called Island Point. The state also gave up 400 acres for a military reservation.

Joseph Totten, later chief engineer of the U.S. Army, supervised construction of the octagonal, 30-foot-tall structure. It would have 125 cannons, and any British ship sailing past would come under heavy fire.

Fort Blunder

Then, two years and $275,000 later, surveyors discovered a problem: The fort was being built on the wrong side of the border.

Under the Treaty of Paris, the 45th parallel marked the border between New York and Quebec. Therefore, the fort designed to protect the United States from Canada was in … Canada.

All work stopped on the fort, and the heretofore unnamed citadel earned the nickname Fort Blunder.

For the next 20 years, enterprising residents of the Rouses Point area looted stones from Fort Blunder and used them for homes, shops and meetinghouses.

The U.S. fixed the problem not by moving the fort, but by moving the boundary line.

After the bloodless and farcical Aroostook War, Daniel Webster in 1842 negotiated the Webster-Ashburton Treaty. The treaty moved the border north. The United States then began to build another fort, named after American revolutionary hero Gen. Richard Montgomery.

Unlike Fort Blunder, the army actually armed and garrisoned Fort Montgomery. Had Britain entered the Civil War, it would have been an important fortification.

Wanna Buy A Fort?

In the 1920s, the United States sold Fort Montgomery at auction. In 1983, Victor Podd, a Montreal shipping magnate, bought it. He offered part of the property to New York State for a historic site, but New York didn’t want it.

After Podd died in 1999, his sons inherited Fort Montgomery. They tried to sell it on eBay and actually got a bid for $5 million, but the deal fell through.

The owners still want to sell Fort Montgomery. You can buy it for less than $1 million.

Image of Fort Montgomery y Mfwills – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=15828989

This story about Fort Blunder was updated in 2019.