February 1957 ‘March 18, 1957-September 6, 1957 May 27, 1957-June 7, 1957 First Plowshare symposium held at Livermore Laboratory. U.N. Disarmament Subcammittee ("of Five") held last series of negotiations in London, Joint Committee on Atomic Energy held hearings on radioactive fallout and its effects on man. May 1957-March 1958 , The Commission conducted Operaticn Plumbbob at the Nevada Test Site, firing thirty-three tests including shot "Rainier," the first detonation contained underground. was also detonated. April-August 1958 July 1, 1958-August 21, 1958 Shot "Smoky" The Commission conducted the thirty- five shot Operation Hardtack I in the Marshall Islands. The "Conference of Experts to Study the Possibility of Detecting Violations of a Possible Agreement on the Suspensicn of Nuclear Tests" held. July 14, 1958 John A. McCone became chairman cf the Atomic Energy Commission. August 22, 1958 President Eisenhower announced moratorium on weapon testing to becin October 31. August-September 1958 The Commission conducted Operation September 1-13, 1958- The United States participated in the in the South Atlantic, detonating three high-altitude nuclear tests. second United Nations Internationa. Conference on the Peaceful Uses cf Atomic Energy in Geneva, Switzerland. September 1958 Lihby-—Cockcroft agreement signed, allowed closer cooperation for mutual defense between United States anc Great Britain. September-October 1958 The Commission conducted Operation Hardtack II at the Nevada Test Site, wnich consisted of thirty-six tests. &Q