His image-holding a rifle on the steps of the Washington state capitol building, flanked by Black men gripping guns as law enforcement officers and others stand by-is one of the most iconic photographs from the Black Power movement during the late 1960s and early 1970s.Elmer Dixon, who at age 17 co-founded the Seattle Chapter of the Black Panther Party, was protesting gun control laws during an era when the Panthers' top mission was to provide armed...