Robert Charles Onco, a member of the Kiowa Tribe of Oklahoma and an American Indian Movement activist, passed into the spirit world on January 31 after a long battle with lung cancer. He was 63 years old.

Bobby Onco, as he was known, was immortalized in a photo that became a symbol the 1973 uprising at Wounded Knee. The photo shows Onco holding a raised AK-47 and smiling broadly. It became famous worldwide as a poster with the words “Remember Wounded Knee” and is archived in the Library of Congress.

The uprising at Wounded Knee—the site of the 1890 massacre of hundreds of men, women and children by the U.S. cavalry—began on February 27, 1973, by Oglala Lakota and AIM activists when approximately 200 Indians seized and occupied the town of Wounded Knee on the Pine Ridge Reservation in South Dakota. The activists were demanding that the U.S. government make good on broken treaties from the 19th and early 20th centuries. It was the beginning of a 71-day occupation and armed conflict with the United States Marshals Service, FBI agents and other law enforcement agencies, who cordoned off the area. The civil rights direct action inspired Indians from all over the country, attracted worldwide media coverage and widespread public sympathy.

Dennis Banks, one of the leaders of the occupation, recalled Onco’s weapon and the relative military strength of the AIM members and the federal government in Ojibwa Warrior: Dennis Banks and the Rise of the American Indian Movement. “One of our men, Bobby Onco… had a AK-47 with a banana clip a souvenir from Vietnam. I don’t think he had any ammo for it; he used it to impress the media and the marshals,” Banks wrote. “Later during the siege we set up a stovepipe, which caused a panic among the feds. ‘Oh my God! Those Indians have a rocket launcher!’ We certainly didn’t have any rockets and almost no ammunition… It was a puny force that faced the mightiest government in the world with its huge arsenal of weapons!”