Hudson's Bay Co. fort at mouth of Moose river, built by Radison & Groseliers in 1671, on or near the site of present Moose Factory, on an island 6 or 7 miles above the open bay or mouth of river. The original fort was surrounded by a square of palisades 100 feet long on each side and 18 feet high with four bastions. It was known as the Hayes Island post. It was the residence of the first Governor of the Company in America, Charles Bayley. On June 11, 1686, it was captured by the French and called by them variously Fort St. Louis, Bourbon, Monsippi, and Monsoni. It was recaptured by the English in 1693 and again retaken by the French 1693 and called Fort St. Louis. In 1696 two English men-of-war retook Fort Moose and other posts in James Bay. About this time the Company was again dispossessed and they demolished the original fort. The site remained unoccupied till 1730. In 1728 Bevan "discovered the island and place where the fort stood formerly". In 1730 the Company rebuilt Fort Moose, the foundations being laid in September 1730, on the same island about &fract12; a mile higher up the river Moose. The name then given "Moose Factory" has been used ever since. The Company list of 1749 names Moose fort and it is named Mouse Fort on Rocque's map 1763 (No. 96). The Factory has been in continuous operation since 1730.

In 1805 the North West Co. erected a fort on the island at the mouth of the Moose river adjoining Moose Factory, but this post was soon abandoned. Maps No. 94, 18, 10, 19, 52 & 93.