On August 22, 1852, at the invitation of Arthur Denny (1822-1899), visiting Bishop Modeste Demers (1809-1871) celebrates Mass in Henry Yesler's sawmill cookhouse. Although the town has no Catholic settlers, the service marks the town's first Christian religious service. (Note: This date is cited and sourced on p. 194, A History of the Catholic Church in the Pacific Northwest by Fr. Wilfred Schoenberg, SJ. There is no doubt that Bishop Demers conducted Seattle's first Christian ceremony, but the date given would seem to precede Henry Yesler's October arrival in Seattle and the later construction of the cookhouse itself. Arthur Denny, in Pioneer Days on Puget Sound, p. 63, refers to the Demers service only as occurring in 1852.)
Bishop Demers was the right-hand assistant to legendary missionary and Oregon Archbishop Francis Norbert Blanchet (1795-1885). Demers had responsibility for everywhere north of the 49th parallel including Vancouver Island, New Caladonia (mainland British Columbia), and Russian America (the future Alaska). He was traveling through Puget Sound in the summer of 1852, on his way to Vancouver Island to assume his responsibilities.
Arthur Denny invited Demers to conduct a service in the new cookhouse of Henry Yesler's unfinished steam sawmill, while noting that there were no Catholics in the neighborhood. This was not actually true: Many local Salish, including Chief Seattle (178?-1866), had already been baptized by Catholic missionaries -- much to the annoyance of some white Protestant settlers and the Methodist missionaries who soon followed.
Bishop Demers celebrated Mass and sermonized on charity, which was at least as rare in Seattle as were white Catholics. He departed the village singularly unimpressed and six years would pass before another priest, Fr. Louis Rossi, visited the town. Finally, in 1867, the Archdiocese grudgingly assigned Fr. Francis Xavier Prefontaine as Seattle's first resident priest.