[4] He was raised by his family in Mackinac Island and then Montreal, until he left home at the age of 13 to work in the fur trade.
They wintered at Fort Confidence on Great Bear Lake and set out eastward in the spring, mapping 100 miles of coastline and naming Victoria Land and Cape Pelly.
For his services in connection with this expedition Dease was given a £100 pension by Queen Victoria, and was rumoured to have been offered a knighthood, which he turned down.
Following the expedition, Dease was given another leave of absence, from 1840 to 1841, during which time he married (on 3 August 1840) and settled on a farm in Côte Sainte-Catherine, near Montreal.
Very steady in business, an excellent Indian trader, speaks several of the Languages well and is a man of very correct conduct and character.
Strong, vigorous and capable of going through a great deal of Severe Service but rather indolent, wanting in ambition to distinguish himself in any measure out of the usual course, inactive until aroused to exertion and over easy and indulgent to his people which frequently occasions laxity of discipline, but when his temper gets ruffled he becomes furiously violent.
His judgement [sic] is sound, his manners are more pleasing and easy than those of many of his colleagues, and altho' not calculated to make a shining figure, may be considered a very respectable member of the concern.
"[8] In a letter addressed to James Hargrave, one Charles Ross had only kind words for Dease: "… I found a most amiable warm hearted, sociable man — quite free from that haughtiness & reserve, which often characterises [sic] those who have little else to recommend them — and if Fortune always favors the Good, he should enjoy an unusual share of her smiles.
He would frequently refer to Dease using demeaning terms in his correspondences, specifically with his brother, Alexander Simpson, and his good friend Donald Ross.
[10] Barr notes that Simpson’s statement is most inaccurate, since Dease successfully operated the New Caledonia District for five years which was known to be a very difficult area to control.
The area relied on salmon rather than pemmican or caribou, and the occasional fishery failures could prove disastrous.
Simpson even goes on to say that he "cannot help regarding him and his followers as dead weight upon the expedition … showing that ten years' experience well applied may be more valuable than that of a life-time.