The Whitman massacre (also known as the Walla Walla massacre and referred to as the Tragedy at Waiilatpu by the National Park Service) was the killing of the American missionaries Marcus Whitman and his wife Narcissa, along with eleven others, on November 29, 1847. They were killed by members of the Cayuse tribe who accused Whitman of having poisoned 200 Cayuse in his medical care. The incident began the Cayuse War. It took place in southeastern Washington near Walla Walla and was one of the most notorious episodes in the U.S. settlement of the Pacific Northwest. Whitman had helped lead the first wagon train to cross Oregon's Blue Mountains and reach the Columbia River via the Oregon Trail, and this incident was the climax of several years of complex interaction between him and the local Native Americans. The story of the massacre shocked the United States Congress into action concerning the future territorial status of the Oregon Country. The Oregon Territory was established on August 14, 1848. The killings are usually ascribed in part to a clash of cultures and in part to the inability of Whitman, a physician, to halt the spread of measles among the Natives. The Cayuse held Whitman responsible for subsequent deaths. The incident remains controversial to this day; the Whitmans are regarded by some as pioneer heroes, while others see them as settlers who had attempted to impose their religion on the Natives and otherwise intrude, even allegedly poisoning them. In 2021, Blaine Harden published "Murder at the Mission" to explore how myths around the massacre and Marcus Whitman were spread by Henry Harmon Spalding who survived the incident. Spalding was able to persuade the US Senate to print an official pamphlet about Whitman which was full of falsehoods. The mythology surrounding the massacre was used as a justification for taking land from the Cayuse people. Background Sahaptin nations came into direct contact with white colonizers several decades before the arrival of the members of the American Board of Commissioners for Foreign Missions (ABCFM). These relations set expectations among the Cayuse for how exchanges and dialogue with whites would operate. Primarily the early Euro-Americans engaged in the North American fur trade and the Maritime fur trade. Marine captains regularly gave small gifts to indigenous merchants as a means to encourage commercial transactions. Later land-based trading posts, operated by the Pacific Fur Company, the North West