First H-Bomb Test

And from Wikipedia:

Ivy Mike was the codename given to the first US test of a fusion device where a major part of the explosive yield came from fusion. It was detonated on November 1, 1952 by the United States at [show location on an interactive map] 11°40′15″N 162°11′53″E / 11.6709, 162.198 on Enewetak, an atoll in the Pacific Ocean, as part of Operation Ivy. The device was the first full test of the Teller-Ulam design, a staged fusion bomb, and is generally considered the first successful test of a hydrogen bomb. Due to its physical size and fusion fuel type (cryogenic liquid deuterium) the Mike device was not suitable for use as a thermonuclear weapon; it was intended as an extremely conservative experiment to validate the concepts used for multi-megaton detonations. A simplified and lightened bomb version (the EC-16) was prepared, and scheduled to be tested in operation Castle Yankee, as a backup in case the non-cryogenic “Shrimp” fusion device (tested in Castle Bravo) failed to work; that test was cancelled when the Bravo device was tested successfully, making the cryogenic designs obsolete.