A feature of modern wars has been the impetus which is given to the development of scientific and technical progress, a phenomenon which is very easily explained by the general urgency of development under the pressure of war requirements, the removal of normal limits on expenditure and the realization of the part that science can play in the development of the engines of war. This was shown to a marked extent in the second world war and amongst the examples can be quoted the vast development of electronic equipment, the emergence of the jet engine as an alternative to the internal combustion engine for motive power and the realization of the use of nuclear power, in the first instance in the form of explosive energy. However, over and above these examples of scientific and technical progress there was one development in the second world war of particular interest, the use of the scientific method of ‘operational research’ (hereafter denoted by O.R.).