1954 - Enewetak Atoll
Operation Castle was a series of high yield thermonuclear weapon design tests. Following the initial experimental demonstration of the Teller-Ulam principles in Operation Ivy (the Sausage device detonated in the Ivy Mike test) both weapon labs rushed to develop a number of deliverable weaponized designs. The original schedule included a weaponized version of the cryogenic fuel system used in Sausage (designated the EC-16, the test device being named JUGHEAD); plus a variety of other extensions and new concepts. One of these new approaches - the use of non-cryogenic "dry" (lithium deuteride) fuel - was a spectacular (and disastrous) success with a yield far exceeding expectations. Some of the other tests were also much larger than expected - in fact the three largest tests ever carried out by the U.S. were all part of Operation Castle.