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Myrnam, Alberta, Canada

Formally Recognized: 1976/06/15

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Other Name(s)

Fort Island
Island Fort
Fort de L'Isle II 1799-1801
Island of Scotland-NW Co. 1800 and 1801
Old Island Fort
Island House

Links and documents

Construction Date(s)


Listed on the Canadian Register: 2009/03/07

Statement of Significance

Description of Historic Place

Fort de l'Isle archaeological site represents the remains of three trading posts used by the XY Company, the North West Company and the Hudson's Bay Company during the years 1799 to 1801. The area is situated northeast of Myrnam, on approximately 43 hectares of land on an island in the North Saskatchewan River. The three forts, commemorated with a cairn and plaque in 1960-61, are currently represented by cellar depressions, chimney rock piles, and assorted cultural materials such as buried wood fragments, animal bones and metal fragments.

Heritage Value

The heritage value of the Fort de l'Isle archaeological site lies in the evidence it provides of three relatively undisturbed examples of the early nineteenth century trading and provisioning posts established on islands in the North Saskatchewan River by the competing XY, North West and Hudson's Bay Companies.

The original fort at Fort de l'Isle ("Island Fort") was established in 1799 by Alexander Mackenzie (nephew of Sir Alexander Mackenzie), after he became a 'wintering partner' in the XY Company (also known as the New North West Company). The purpose of the fort was to compete with the trade conducted downriver at the paired forts of Buckingham House (Hudson's Bay Company) and Fort George (North West Company). By 1801, Duncan McGillivary at Fort George decided to move the North West Company's trade to the island and commissioned a man named Decoigne to build the fort. James Hughes was put in charge of the new fort. The Hudson's Bay Company also built a fort on the island at about this time, putting Henry Hallett in charge.

The unique events that transpired between competing traders housed at this site influenced Canadian legal history and augment the heritage value of the site. The three forts at Fort de l'Isle were only occupied for a short period of time. Their coexistence was disrupted by a disagreement between clerks of the Hudson's Bay Company and the XY Company during the winter of 1802. Although the three companies had agreed to avoid trouble by trading only with Aboriginal people who had been granted credit at their particular post, Hudson's Bay Company clerk James King found this unprofitable. As a result, while he and XY Company clerk were trading at a nearby Aboriginal camp, King insisted on taking some of the furs LaMothe had collected in payment. After a struggle, LaMothe killed King in an act of self-defence. LaMothe travelled to Montreal to submit himself for trial and was convicted by a grand jury for murder. As Fort de l'Isle lay outside the boundaries of Upper and Lower Canada, however, it was unclear if a Canadian jury could rule on the matter. As a result, LaMothe was eventually set free.

The trial of LaMothe, and the legal controversy it sparked, led to the enactment of the Canada Jurisdiction Act in 1803 by the Imperial Parliament of England, to ensure Canadian courts were provided with jurisdiction over crimes committed outside Upper and Lower Canada. After 1811, the Act was used as weapon by both the Hudson's Bay Company and the North West Company during their conflicts, when members of both companies were sworn as magistrates and began a campaign of arresting competitors to send them east for trial and remove them from western fur trading activities.

After the LaMothe-King incident in 1802, the Hudson's Bay Company and the North West Company abandoned Fort de l'Isle in favour of the paired forts known as Fort Vermilion and Paint Earth House. In 1804, the XY Company was absorbed by the North West Company. As late as 1808, however, the Hudson's Bay Company still had "Island Fort" or "Island House" listed in their records, although they had transferred the name to the location at Fort Vermilion. In David Thompson's journals of 1800, the area of the three forts was identified as "Island of Scotland - NWCo. 1800 and 1801", and it may also be the location identified in his 1808 journals as "Old Island Fort". More recently, the Fort de l'Isle location on Fort Island in Alberta is referred to as Fort de l'Isle II, to distinguish it from an earlier 1785-1794 Fort de l'Isle I established on Pine Island in the Saskatchewan portion of the North Saskatchewan River.

Sources: Alberta Culture and Community Spirit, Historic Resources Management Branch (File: Des. 705); Foster, Hamar. 1990. "Long-Distance Justice: The Criminal Jurisdiction of Canadian Courts West of the Canadas, 1763-1859" in The American Journal of Legal History, 34(1): 1-48.

Character-Defining Elements

The character-defining elements of the Fort de l'Isle archaeological site include such features as:
- the archaeological remains consisting of several features and buried materials which represent the co-occurrence of three competing fur trade forts in a very small land area, a unique combination in Alberta which permits an opportunity to study similarities and differences between the settlement and cultural practices of the major trading companies in the Canadian West;
- the relatively inaccessible location of the site, combined with continued inundation from river silting, has provided an environment which may be very good for the preservation of cultural materials that can provide information about the daily lives and economies of people at trading forts in the late eighteenth and early nineteenth centuries in Canada;
- the historic records available for site which provide background on the site's relationship to the history of the fur trade in western Canada and detail the events relating to the trading practices at two of the three forts, which were the impetus for a significant legal debate in 1802-1803, and resulted in the enactment of the Canada Jurisdiction Act (1803).




Recognition Authority

Province of Alberta

Recognition Statute

Historical Resources Act

Recognition Type

Provincial Historic Resource

Recognition Date


Historical Information

Significant Date(s)


Theme - Category and Type

Developing Economies
Trade and Commerce

Function - Category and Type



Commerce / Commercial Services
Trading Post

Architect / Designer




Additional Information

Location of Supporting Documentation

Alberta Culture and Community Spirit, Historic Resources Management Branch, Old St. Stephen's College, 8820 - 112 Street, Edmonton, AB T6G 2P8 (File: Des. 705)

Cross-Reference to Collection

Fed/Prov/Terr Identifier




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