The Canso Islands lie off the eastern tip of mainland Nova Scotia beside rich Atlantic fishing grounds and sheltered anchorages. Mi’kmaq communities used these waters long before Europeans arrived. From the sixteenth century, French, Basque, and other Atlantic fishermen worked seasonally around the islands, drying and curing cod for overseas markets. The geography that made Canso valuable also made it contested: a small archipelago close to the fishery could support boats, stores, stages, and defenses while controlling access to an economic resource of international importance.

After Britain gained mainland Nova Scotia under the Treaty of Utrecht in 1713, New England merchants expanded their presence at Canso. Fishing rooms and trading facilities developed on the islands, while relations with French and Mi’kmaq interests remained tense. British authorities built fortifications on Grassy Island beginning around 1720, including works known at different times as Fort William Augustus, Fort Phillips, and later Fort Prince William. These defenses were modest and repeatedly vulnerable, revealing how difficult it was to hold a remote station dependent on the sea for supplies.

Canso became a target during imperial conflicts. French and Mi’kmaq forces attacked the settlement, and in 1744 a major raid destroyed the British post at the opening of King George’s War. Yet the harbor soon served another military purpose. In 1745 it became the staging point for the New England and British expedition led by William Pepperrell and Peter Warren against Louisbourg. The capture of that French fortress temporarily altered the balance in Atlantic Canada, showing how an outpost built around cod could become central to a campaign for imperial control.

The islands’ prominence declined as military and commercial patterns changed, but archaeological remains preserved the close relationship between fishery and fortification. Building foundations, cellars, artifact scatters, defensive earthworks, and shoreline features record seasonal labor and permanent occupation. Canso Islands was designated a national historic site in 1925 for its importance to the early fishery and Anglo-French struggle. Grassy Island Fort received separate national recognition in 1962, while remaining part of the same historical landscape interpreted by Parks Canada.

Visitors begin at the mainland interpretation center and, when conditions permit, cross to windswept Grassy Island. Trails connect the ruins of the fort and fishing settlement with views across the anchorages and open Atlantic. The sparse landscape is essential evidence: distance, weather, water, and access to fish explain both the settlement’s prosperity and its insecurity. Canso’s history links Indigenous use, European migration, commercial extraction, warfare, and archaeology, demonstrating how the North Atlantic cod trade shaped communities and imperial strategy centuries before Canada existed as a nation.