1952 - Enewetak Atoll
From early 1951 onward, these two parallel efforts to develop high yield weapons were focused on a Pacific Proving Ground test series for late in 1952. This series - Operation Ivy - exploded the two largest bombs tested up to that time. It inaugurated the thermonuclear age with the first "true" thermonuclear test (code name Mike), which was considerably more powerful than all the high explosives used in two World Wars put together. Ivy also tested the highest yield pure fission weapon ever exploded.