The Tsar Bomba is the King of all Bombs. No other man made explosion has come close to the power of 1961 Tsar Bomba test. Tested by the Soviet Union, its yield was ten times greater then all of the munitions exploded during World War 2. The irony of the Tsar bomb was that despite its power, it was useless as a weapon.
The actual development of the bomb began in July 1961. The device was designed to have a yield of 100 megatons, as requested by Soviet Premier Nikita Khrushchev. The Soviet Union did not make the development of the bomb secret, in fact, it was well publicized. Nikita Khrushchev repeatedly made claims the Soviet Union had a 100 megaton bomb, and that a scaled-down version of the device would be tested.
A nuclear testing moratorium suspended all tests since 1958. The decision to resume testing by the Soviet Union was a calculated one, designed to coincide with the recent erection of the Berlin Wall in August of 1961. Weapons designers and scientists conjured up new kinds of nuclear weapons designs to be tested, including the Tsar Bomba.