When I opened the manila envelope that contained these certificates, I assumed that each certificate was for one bomb. It was years later that I discovered information on the Internet about the extent of the explosions, radiation, fallout and ground contamination. Operation Hardtack consisted of a total of 72 explosions.
In 1958 the arms race proceeded, with the enormous weapons production infrastructure and weapons labs operated at full speed. Hardtack I included 35 tests at the South Pacific Proving Grounds, the largest test series so far.
Partly this burst of testing activity was due to building pressure for an imminent test moratorium, leading the weapons labs to rush as many device types to the test range as possible. A total of 35.6 megatons were shot during this series.
Hardtack II at the Nevada Test site exploded 37 tests. “This series introduced underground testing as a routine procedure. The intention was to reduce the fallout effects of the testing, which were raising great concern, but the “underground” testing procedures were still relatively primitive. These shots were called “roman candles” since the incandescent gas from the fireball was ejected as a jet from the mouth of the shaft. Obviously fallout containment was much less than perfect, but most of the fission product was nonetheless deposited in the shaft instead of escaping.”