From 1827 to 1833, Fort Langley played a major role in the British coastal offensive against the American traders. More than half of the 3,000 beaver collected by the Hudson's Bay Company on the coast in 1831, were from the new Fraser River establishment. Under the astute direction of Chief Trader Archibald McDonald, Langley systematically undersold its American competitors and soon commanded the trade with Indian tribes throughout Vancouver Island, the Fraser River and Puget Sound.
As its immediate area became exhausted, Fort Langley's primary function shifted from fur collecting to provisioning. A network of posts and vessels was gradually built up to expand the Company's control of the coast and the Langley fishery and farm supplied many of their basic needs.
Salmon, abounding in the Fraser River, had long been a staple of coast Indian and fur trader, and could be cheaply traded with the Indians for "vermilion, rings and other trifles". Salting and packing salmon became an industry under Chief Trader McDonald and his successor James Murray Yale. By 1838 Langley supplied all the salt salmon required by the Company's operations west of the Rockies. As the Hudson's Bay Company became linked to the wider commerce of the Pacific, Langley-cured salmon found its way to markets in the Sandwich Islands (Hawaii) and Australia.
Farming was begun on the fertile prairie 11 kilometres from the fort, in the area then known as Langley Prairie. Crops were frequently washed out in the low-lying land, but the agricultural operations steadily expanded until the Langley farm covered over 800 hectares. Producing potatoes, barley, peas and wheat and maintaining a stock of 200 pigs and 500 head of cattle, it supplemented the produce of many Pacific forts and provided food for the SS Beaver and other Company vessels.
In 1839, the Hudson's Bay Company agreed to lease the Alaskan Panhandle from the Russian American (Fur) Company for an annual rent in otter skins and specified farm products. Fort Langley was called upon to produce wheat and butter for the Russian contract. In order to facilitate farming operation, the original fort, now in a dilapidated condition, was abandoned and a new one built four kilometers upstream, closer to the large prairie.