Mackenzie had been sent to replace Peter…
July 1789 CE
Mackenzie had been sent to replace Peter Pond, a partner in the North West Company.
From Pond, he had earned that the First Nations people understand that the local rivers flowe to the northwest.
Acting on this information, he sets out by canoe on the river known to the local Dene First Nations people as the Dehcho, (Mackenzie River) on July 10, 1789, following it to its mouth in the hope of finding the Northwest Passage to the Pacific Ocean.
As he ends up reaching the Arctic Ocean on July 14, it is conjectured that he named the river "Disappointment River" as it did not lead to Cook Inlet in Alaska as he had expected.
The river will later be renamed the Mackenzie River in his honor.