The French built Fort Menagoueche in 1751 because they understood a geographic truth that had shaped conflict in the region for a century. The Saint John River was not just a waterway; it was the corridor between the Bay of Fundy and Quebec City. If the British controlled the river's mouth, they could cut off the supply lines and communications that connected French Acadia to the heartland of New France. The Marquis de la Jonquiere ordered the fort's construction as part of a three-fort defensive chain: Fort Gaspareaux at Baie Verte, Fort Beausjour at the Isthmus of Chignecto, and Fort Menagoueche at the river's mouth. Communication between Menagoueche and Beausjour ran at first along an ancient portage route, but by 1754 a proper road linked the two posts. In summer, ships could reach Quebec, Louisbourg, and France directly from the harbour. The fort itself was modest -- effectively a fortified warehouse with a small garrison -- but its position was everything.

The Saint John River valley was home to a population the British found deeply inconvenient. Acadians had lived there almost continuously since the early seventeenth century, and after the British conquest of peninsular Nova Scotia in 1710, more Acadians migrated upriver to stay beyond British reach. These were the most resistant Acadians in the region -- people who refused the oath of allegiance and maintained close ties with the Maliseet and Mi'kmaq. The Maliseet militia, operating from their base at Meductic, had conducted effective warfare against New England throughout the colonial wars. As late as 1748, only twelve French-speaking families lived on the river, but the military alliance between the Acadians, Maliseet, and Mi'kmaq gave the valley a defensive strength that far exceeded its population. In 1749, at the start of Father Le Loutre's War, Boishebert personally rebuked a British naval officer named John Rous who tried to assert authority at the river mouth.

By 1755, the British were tightening their grip. In April of that year, a British captain named Cobb stumbled upon the French schooner Marguerite while searching for a wrecked vessel at Port La Tour. The Marguerite was carrying war supplies up to Boishebert at Fort Menagoueche. Cobb sailed back to Halifax with the intelligence, and Governor Charles Lawrence ordered a blockade of the harbour until the warship HMS Vulture could arrive to seize the French prize. The discovery of the Marguerite revealed just how actively the French were resupplying their garrisons -- and how thin the line was between maintaining those supply routes and losing them entirely. When Fort Beausjour fell to Robert Monckton in June 1755, Monckton immediately sent a detachment under John Rous to take Fort Menagoueche. The fort's destruction was assured. The only question was who would do the destroying.

Boishebert chose fire over surrender. With 65 Canadians and 120 Indigenous allies, he had enough men for ambush and raid, but not for a pitched defense against regulars. He torched Fort Menagoueche and withdrew upriver, where the forest and the river bends gave guerrilla fighters every advantage. His first strike came at the Battle of Petitcodiac. The burning of Fort Menagoueche left Louisbourg as the last French fort in Acadia -- an island fortress that would itself fall three years later. In 1758, Monckton returned to the Saint John River mouth and reconstructed the ruins as Fort Frederick, beginning a new chapter in the endless cycle of fortification, destruction, and rebuilding that defined this particular point of land. Today, a monument at the site in Saint John commemorates the succession of forts that occupied this ground. The landscape gives no hint of the fortified warehouse that once stood here, the supply ships that once anchored in the harbour, or the commander who chose to leave nothing for the enemy but smoke.