Fertig became an anti-segregationist activist early in his life in Chicago, and eventually became active throughout the country, including the Southern United States, and he played an organizing and leading role among civil rights activists, including the Freedom Riders. He was arrested, severely beaten and jailed for his activism in Selma, Alabama in 1961. He helped organize the March on Washington for Jobs and Freedom on August 28, 1963. He was a community organizer and first Executive Director of the Southeast Neighborhood House in Anacostia, D.C., then later became Executive Director of the Washington Metropolitan Planning and Housing Association until 1973, when he moved to Los Angeles, California.