Its most significant action was an expedition organized by Massachusetts Governor William Shirley that besieged and ultimately captured the French fortress of Louisbourg, on Cape Breton Island in Nova Scotia, in 1745.

The War of Jenkins' Ear (named for a 1731 incident in which a Spanish commander sliced off the ear of British merchant captain Robert Jenkins and told him to take it to his king, George II) broke out in 1739 between Spain and Great Britain, but was restrained to the Caribbean Sea and conflict between Spanish Florida and the neighboring British Province of Georgia.

Britain was drawn diplomatically into that conflict in 1742 as an ally of Austria and an opponent of France and Prussia, but open hostilities between them did not take place until 1743 at Dettingen.

Concerned about their overland supply lines to Quebec, they raided the British fishing port of Canso on May 23, and then organized an attack on Annapolis Royal, the capital of Nova Scotia.

But French forces were delayed in departing Louisbourg, and their Mi'kmaq and Maliseet First Nations allies, together with Father Jean-Louis Le Loutre, decided to attack on their own at Fort Anne in early July.

Annapolis had received news of the war declaration, and the British forces were somewhat prepared when the First Nations warriors began besieging Fort Anne.

Beset by storms, disease, and finally the death of its commander, the Duc d'Anville, the expedition's survivors returned to France in tatters without reaching its objective.

[citation needed] According to the Treaty of Aix-la-Chapelle, Louisbourg was returned to France three years later, in exchange for the city of Madras in India, which had been captured by the French from the British.