A Really BIG Hammer for December 2nd

December 2, 1942 – Manhattan Project: A team led by Enrico Fermi initiates the first self-sustaining nuclear chain reaction. The Manhattan Project was the codename for a project conducted during World War II to develop the first atomic bomb, before the Germans or the Japanese. The project was led by the United States, and included participation from the United Kingdom and Canada.

The uranium bomb was a gun-type fission weapon. It worked by mechanically assembling the critical mass from two subcritical masses of uranium-235: a "bullet" and a "target". The chain reaction resulting from collision of the "bullet" with the "target" released tremendous energy, producing an explosion, but also blew apart the critical mass and ended the chain reaction. The configuration of the critical mass determined how much of the fissile material reacted in the interval between assembly and dispersal, and therefore the explosive yield of the bomb. Even a 1% fission of the material would result in a workable bomb, equal to thousands of tons of high explosive. A poor configuration, or slow assembly, would release enough energy to disperse the critical mass quickly, and the yield would be greatly reduced, equivalent to only a few tons of high explosive.

The method was so certain to work that no test was carried out before the bomb was dropped over Hiroshima, though extensive laboratory testing program was undertaken to make sure the fundamental assumptions were correct. The bomb that was dropped used all the existing extremely highly purified uranium-235, and even most of the less highly purified material, so there was none available for such a test. The bomb's design was known to be inefficient and prone to accidental discharge.

December 2, 1976 – Fidel Castro becomes President of Cuba: One of the primary leaders of the Cuban Revolution, Castro served as the Prime Minister of Cuba from February 1959 to December 1976, and then as the President of the Council of State of Cuba and the President of Council of Ministers of Cuba until his resignation from the office in February 2008. He served as First Secretary of the Communist Party of Cuba, from 1965 until 2010, when he retired for health reasons.

While studying law at the University of Havana, he began his political career and became a recognized figure in Cuban politics. His political career continued with nationalist critiques of the president, Fulgencio Batista, and of the United States' political and corporate influence in Cuba. He gained an ardent, but limited, following and also drew the attention of the authorities. He eventually led the failed 1953 attack on the Moncada Barracks, after which he was captured, tried, incarcerated, and later released.

He then traveled to Mexico to organize and train for an invasion of Cuba to overthrow Batista's government, which began in December 1956.  The Granma arrived in Cuba on 2 December 1956. It arrived in Cuba two days later than planned because the boat was heavily loaded, unlike during the practice sailing runs. After arriving and exiting the ship, the band of rebels began to make their way into the Sierra Maestra mountains, a range in southeastern Cuba. Three days after the trek began, Batista's army attacked and killed most of the Granma participants, but a small number escaped. While the exact number is in dispute, no more than twenty of the original eighty-two men survived the initial bloody encounters with the Cuban army and succeeded in fleeing to the Sierra Maestra mountains.

The group of survivors included Fidel Castro, Che Guevara, Raúl Castro, and Camilo Cienfuegos. The dispersed survivors, alone or in small groups, wandered through the mountains, looking for each other. Eventually, the men would link up again - with the help of peasant sympathizers - and would form the core leadership of the guerrilla army. Castro subsequently came to power as a result of the Cuban Revolution, which overthrew the U.S.-backed dictatorship of Batista, and shortly thereafter became Prime Minister of Cuba.

Sources for this week's Hammer of Thor:
http://en.wikipedia.org/wiki/Manhattan_Project
http://en.wikipedia.org/wiki/Fidel_Castro
http://en.wikipedia.org/wiki/Cuban_Revolution