France tests its first atomic bomb to become the world's fourth nuclear power, code named Gerboise Bleue

Gerboise Bleue ("blue jerboa") was the name of the first French nuclear test.

It was an atomic bomb detonated in the middle of the Algerian Sahara desert on 13 February 1960, during the Algerian War (1954-62). General Pierre Marie Gallois was instrumental in the endeavour, and earned the nickname of père de la bombe A ("father of the A-bomb").

Gerboise is the jerboa, a desert rodent, while blue is the first color of the French tricolor flag. So the second and third bombs were named respectively "white" (Gerboise Blanche) and "red" (Gerboise Rouge).

With Gerboise Bleue, France became the fourth nuclear power, after the United States, the USSR, and the United Kingdom. Gerboise Bleue was by far the largest first test bomb up to that date, larger than the American "Trinity" (20 kt), the Soviet "RDS-1" (22 kt), or the British "Hurricane" (25 kt). The yield was 70 kilotons, bigger than these three bombs put together. The second most powerful first-test bomb was "Chagai-I", detonated by Pakistan in 1998, at 40 kilotons.

In comparison, Fat Man, the Nagasaki bomb, was 22 kilotons, one-third as powerful.

Only two other A-bombs tested in the Sahara facilities were more powerful: "Rubis" (<100 kt, 20 October 1963), and "Saphir" (<150 kt, 25 February 1965). Both were exploded underground at the Tan Afella facility.

All other French atomic-bomb tests, including Canopus, were done in French Polynesia from 1966 to 1996. The last bomb, Xouthos (<120 kt), was exploded on 27 January 1996.

As an atomic yield cannot be precisely estimated, the French army planned an explosion between 60 and 70 kt. Gerboise Bleue was a total success, yielding the full designed power.

Due to increasing criticism, France stopped its atmospheric tests in the desert, and conducted further underground tests months after Algerian independence in 1962 according to secret agreements with the FLN.

From February 1960 to April 1961, France tested a limited number of atmospheric bombs in Reggane facility's C.S.E.M. (Centre Saharien d'Expérimentations Militaires, or "Saharan Center for Military Experiments"): the four Gerboise bombs. Three of them were only engins de secours ("emergency devices"), with yields deliberately reduced to less than 5 kilotons. With the underground tests the sequence designation was changed to jewel names, starting in November 1961 with "Agathe" (agate; <20 kt). On 1 May 1962, during the second test, the "Beryl incident" (incident de Béryl) occurred, which was declassified many years later.

Five months after the last Gerboise A-bomb, the Soviet Union responded by breaking its atmospheric tests moratorium, settled de facto since late 1958 with the United States and the United Kingdom. The USSR conducted many improvement tests, starting in September 1961 with a series of 136 large H-bombs. The series included the most powerful bomb ever tested, the 50-megaton (50,000 kt) "Tsar Bomba", which was detonated over Novaya Zemlya. Although the Soviet Union mastered H-bomb technology back in 1955, this "record" could have been meant as an answer to France emerging as a third Western force with nuclear power in the Cold War context.

Following the USSR, the United States reactivated its own atmospheric test program with a series of 40 explosions from April 1962 to November 1962. This series included two powerful H-bombs topping 7.45 Mt and 8.3 Mt.

China also launched its own nuclear program, resulting in the A-bomb "596" (22 kt) tested on 16 October 1964, and the H-bomb Test No. 6 (3.3 Mt), tested 17 June 1967.

In 1968, France detonated its first thermonuclear weapon, Canopus (2.6Mt), at the new facility at Fangataufa, a desert atoll in French Polynesia.