Final answer:
The Christian mission in the Willamette Valley was part of the westward expansion and missionary activity in 19th-century America. No specific individual or organization is singled out in the provided information for starting this mission.
Step-by-step explanation:
The Christian mission in the Willamette Valley of Oregon was started by American missionaries. However, specific individuals or a particular church responsible for this mission are not mentioned in the provided reference materials. The region saw a significant increase in American settlers due to the popular concept of Manifest Destiny, and various missionaries were part of the wave of people moving westward. It was during this westward expansion that Christian missions were established to convert local Native American populations and serve the settler communities.
In the broader context of the 19th century, missionaries and circuit riders played a substantial role in spreading Christianity across the United States, which included the Pacific Northwest during a time when the U.S. and Britain were contending for the territory. The information provided alludes to general missionary activity without attributing the establishment of a particular mission in the Willamette Valley to a specific individual or organization.