Incendiary bombs 4-pound magnesium

The German incendiary bombs used a kilogram of magnesium [2.2 pounds], but magnesium was in short supply. Starting in September 1941, NDRC set out to produce an incendiary bomb at least as effective as the... 

The outbreak of war in Europe called attention as never before to the possibilities of aerial incendiaries. German planes began to shower London with magnesium electron bombs and no-kilo oil bombs, and the English replied with their 4-pound magnesium munition. The United States Army could no longer afford to neglect the development and production of incendiary bombs. ... 

Aircraft dropped more 4-pound magnesium bombs than all other incendiary bombs put together. Almost thirty million fell on Europe, and almost ten million on Japan, causing damage that ran into astronomical figures. 

The Ordnance Department was aware of these facts when it began development of 4-pound magnesium bombs. It planned a substitute bomb having the same dimensions and incendiary filling as the M50, but with a steel case in place of magnesium. It sent the plans and models of the substitute bomb, called the M54, to the CWS when that service took over responsibility for incendiaries, and the bomb was completed by the technical staff at Edgewood. 

Four-pound magnesium bombs and other small incendiaries were not dropped individually, but in clusters which were held together by devices called adapters. 

An example of a munition that was standardized but never employed is the incendiary leaf, developed in 1941-42 by the CWS and the Celanese Corporation of America. It was intended for dry grain fields, forests, thatched roofs, and other targets that would burn easily. As with the 4-pound magnesium bomb, the idea came from the British. Leaves were made in the form of disks, eight inches in diameter, one-fourth of an inch thick, and composed of pyroxylin. One type had pellets of white phosphorus attached to it, embedded in a putty-like material. When containers... 

Surprising as it may seem, the first great incendiary raids of World War II were not carried out with large bombs, but with small missiles weighing only a few pounds. In September 1940 the Germans showered London with 1-kg. magnesium alloy bombs, starting innumerable fires,... 

Four types of 500-pound bombs looked suitable on paper, and to determine which was best the technical staff, with co-operation from the Ordnance Department, set to work on all of them. One had a thick steel casing filled with napalm and carrying a HE-white phosphorus burster igniter. Two others were identical with the above except for the casing, one being of thin steel, the other of magnesium. The fourth bomb was filled with a number of small incendiary units that scattered when the bomb exploded. 

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