The first large-scale thermonuclear detonation—the 10.4-megaton Ivy Mike test of 1 November 1952, at the U.S. Atomic Energy Commission Pacific Proving Grounds on Eniwetok Atoll in the Marshall Islands. The test was designed to confirm, at the megaton level, the effectiveness of the newly discovered “Teller-Ulam” radiation “trigger,” an advance that made fusion explosions practicable. The explosion was unexpectedly powerful, five hundred times more so than the fission-technology Fat Man of 1945. . . .
Ivy Mike was not a “bomb” but a test-bed; the Soviet Union made the same breakthrough the next year. Successive tests were devoted to developing serviceable thermonuclear weapons, or “hydrogen bombs,” ultimately producing the vast arsenals that make the subject of a group of articles in this issue—reductions in nuclear weapons. . . .