In 1966 Curcio became involved in protests against U.S. involvement in the Vietnam War. In 1969 he refused to apply for a degree from the university, married fellow leftist Margherita Cagol, and went to Milan, where he and his wife joined the violent extremist organization the Metropolitan Political Collective (MPC). Embracing the idea of armed revolt against the state, Curcio, Cagol, and Alberto Franceschini formed the Red Brigades in 1970. It would become Italy's major leftist terrorist organization in the postwar years.
The Red Brigades was a highly secretive and well-structured organization. Its activities included bombings, robberies, kidnappings, and maiming as terror weapons against the government. The Red Brigades' terrorist tactics reached a peak with the kidnapping of Judge Mario Sossi, who was later freed without any concessions being granted the terrorists. On 8 September 1974, Curcio was arrested as part of an undercover sting. But in February 1975 a commando-like operation led by Cagol succeeded in freeing him.
Police activity against the Red Brigades became more effective following the kidnapping of industrialist Vallarino Gancia on 5 June 1976; the following day a Carabinieri raid freed the hostage and killed Cagol. In January 1976 Curcio was wounded, captured by police, and jailed. With its leader and ideological head in captivity, the Red Brigades went into decline. Curcio remains in prison but in 1994 was allowed to take up day work as a publisher in Rome, infuriating many Italians.
Moss, David. The Politics of Left-Wing Violence in Italy, 1969–1985. New York: St. Martin's, 1989.