Operation Auca was an attempt by five Evangelical Christian missionaries from the United States to bring Christianity to the Waodani or Huaorani people of the rain forest of Ecuador. The Huaorani, also known pejoratively as Aucas (a modification of , the Quechua word for 'savages'), were an isolated tribe known for their violence, against both their own people and outsiders who entered their territory. With the intention of being the first Christians to evangelize the previously uncontacted Huaorani, the missionaries began making regular flights over Huaorani settlements in September 1955, dropping gifts, which were reciprocated. After several months of exchanging gifts, on January 3, 1956, the missionaries established a camp at "Palm Beach", a sandbar along the Curaray River, a few kilometers from Huaorani settlements. Their efforts came to an end on January 8, 1956, when all five—Jim Elliot, Nate Saint, Ed McCully, Peter Fleming, and Roger Youderian—were attacked and speared by a group of Huaorani warriors. The news of their deaths was broadcast around the world, and Life magazine covered the event with a photo essay.
The deaths of the men galvanized the missionary effort in the United States, sparking an outpouring of funding for evangelization efforts around the world. Their work is still frequently remembered in evangelical publications, and in 2006 was the subject of the film production End of the Spear. Several years after the death of the men, the widow of Jim Elliot, Elisabeth, and the sister of Nate Saint, Rachel, returned to Ecuador as missionaries with the Summer Institute of Linguistics (now SIL International) to live among the Huaorani. This eventually led to the conversion of many, including some of those involved in the killing.
Waorani
The Waorani around the time of Operation Auca were a small tribe occupying the jungle of Eastern Ecuador between the Napo and Curaray Rivers, an area of approximately 20,000 square kilometers (7,700 mi²). They numbered approximately 600 people, and were split into three groups, all mutually hostile—the Geketaidi, the Baïidi, and the Wepeidi. They lived on the gathering and cultivation of plant foods like manioc and plantains, as well as fishing and hunting with spear and blowgun. Family units consisted of a man and his wife or wives, their unmarried sons, their married daughters and sons-in-law, and their grandchildren. All of them would reside in a longhouse, which was separated by several kilometers from another longhouse in which close relatives lived. Marriage was always endogamous and typically between cousins, and arranged by the parents of the young people.
Before their first peaceful contact with outsiders () in 1958, the Huaorani fiercely defended their territory. Viewing all as cannibalistic predators, they killed rubber tappers around the turn of the 20th century and Shell Oil Company employees during the 1940s, in addition to any lowland Quechua or other outsiders who encroached on their land. Furthermore, they were prone to internal violence, often engaging in vengeance killing of other Huaorani. Raids were carried out in extreme anger by groups of men who attacked their victims' longhouse by night and then fled. Attempts to build truces through gifts and exchange of spouses became more frequent as their numbers decreased and the tribes fragmented, but the cycle of violence continued.
Missionaries
Jim Elliot first heard of the Huaorani in 1950 from a former missionary to Ecuador, and afterwards indicated that God had called him to Ecuador to evangelize the Huaorani. He began corresponding with his friend Pete Fleming about his desire to minister in Ecuador, and in 1952 the two men set sail for Guayaquil as missionaries with the Plymouth Brethren. For six months they lived in Quito with the goal of learning Spanish. They then moved to Shandia, a Quechua mission station deep in the Ecuadorian jungle. There they worked under the supervision of a Christian Missions in Many Lands missionary, Wilfred Tidmarsh, and began exposing themselves to the culture and studying the Quechua language.
Another team member was Ed McCully, a man Jim Elliot had met and befriended while both attended Wheaton College. Following graduation, he married Marilou Hobolth and enrolled in a one-year basic medical treatment program at the School of Missionary Medicine in Los Angeles. On December 10, 1952, McCully moved to Quito with his family as a Plymouth Brethren missionary, planning to soon join Elliot and Fleming in Shandia. In 1953, however, the station in Shandia was wiped out by a flood, delaying their move until September of that year.