The Battle of Fort Beaus?jour marked the opening of a British-American offensive in North America in the Seven Years' War. From July 3 to the French capitulation of July 16, 1755, a powerful British army under command of Lieutenant-Colonel Robert Monkton staged out of nearby Fort Lawrence and besieged the garrison of Fort Beaus?jour in the goal of opening the Isthmus of Chignecto to British control.

Although de Vergor, subject to intense bombardment, defied the British for two weeks, there was little the French could realistically do to lift the siege in the face of overwhelming British superiority. On July 16, British mortar fire breached defective fortification works and badly mauled the garrison. de Vergor surrendered.

The next day, the French abandoned nearby Fort Gaspareau, severing communications with Acadia. However, the campaign of 1755 was not strategically decisive and did little to threaten New France's territorial integrity, with Edward Braddock's simultaneous thrust into the Ohio Valley ending in disaster at the Battle of the Monongahela.