Why did Narcissa and marcus whitman fail in their efforts to convert the cayuse indians to christianity

Narcissa Prentiss Whitman was an American missionary in the Oregon Country of what would become the state of Washington. Along with Eliza Hart Spalding, she was the first European-American woman to cross the Rocky Mountains in 1836 on her way to found the Protestant Whitman Mission with her husband, Marcus, near modern-day Walla Walla, Washington.