[1] In the 1830s, John McLoughlin sent letters from French Canadian Catholic employees of the Hudson's Bay Company requesting from Bishop Provencher of the Red River colony to send priests to what was then known as the Oregon Country.

The missionaries were instructed by Archbishop Joseph Signay of Quebec: "In order to make yourselves sooner useful to the natives... you will apply yourselves... to the study of the Indian languages... so as to be able to publish a grammar after some of your residence there.

Arriving on 18 November at Fort Nez Percés, a Hudson's Bay Company fur trade outpost located in the present state of Washington, Blanchet celebrated Masses and baptized three Roman Catholic converts.

The first Catholic Mass south of the Columbia river (in the Oregon Country) was celebrated at the St. Paul church on January 6, where Blanchet remained for five weeks.

[7] Blanchet was the first non-Native American to make an overnight stay on Whidbey Island in May 1840, where he offered Mass for several tribes at an outdoor altar; he had been invited by Chief Tslalakum.

[10][8] In February 1841 several gatherings were convened to determine the fate of recently deceased Ewing Young's estate, the first of the Champoeg Meetings which two years later saw formation of the Provisional Government of Oregon.

Included in the considered government was the position of governor, which led Blanchet to counter propose a political system with a judge as the highest authority.

[11] During the subsequent meeting held at David Leslie's home near Champoeg[5] on the next day Blanchet was selected to chair a committee to draft the laws of government.