Long before the war it was evident that science would have much to contribute to the development of military equipment, and it was no surprise that research found such wide applications to the technically difficult but fundamentally amenable problems of Radar, Anti-aircraft and Fragmentation, to name only a few. These problems offered great possibilities to the well-established methods of the physical sciences. By contrast, the complexities of military tactics proved for a long time intractable, since even the smallest battle is a bewildering compound of variables, and new methods had therefore to be worked out before there could be any hope of results. In spite of these difficulties, each of the six Operational Research Sections set up at one time or another with the Field Armies achieved a considerable measure of success. But where the future is concerned, it is not so much the results they achieved, however valuable, as the methods they used, that will matter. For the superficial details of battle may be altered in a moment by the introduction of a new weapon, while the underlying principles of warfare scarcely change from one century to the next.