Scientific investigation--that is, the collection, verification, and classification of facts--follows the recurrent procedure of successive analysis, hypothesis, theory, and test. The application of this process to the campaigns of history reveals fundamentals common to all, irrespective of whether the sphere of action has been land, sea, or air. In the ceaseless struggle for supremacy between the offense and the defense, great technological changes have taken place. The successful conduct of war, however, has always depended on effective operations for the creation or maintenance of favorable military situations, whose essential elements have remained unchanged throughout the years (see page 46). These fundamental considerations (see page 28), whatever the detailed form of their presentation, are the basis for the successful conduct of war. The need of such a basis has been felt from very early times. It was not, however, until the early part of the Nineteenth Century that students of warfare appear to have recorded the view that the conduct of war is susceptible of reduction to scientific analysis, and that only through a reasoned theory can the true causes of success and failure be explained. Such a scientific analysis of any subject has for its chief practical aim the improvement of the art, or practice, of that subject. Forming an important part of the science of war are those new developments in weapons and in other technological fields which, with the passage of time, have brought about great changes in methods of waging war. It is only through founding the art of war--the application of the science of war to actual military situations--on the fundamental truths discovered through the science of war, that changes in method, due to technological evolution, can be made most effective. In preparing for war, the only practicable peacetime tests are usually restricted to those afforded by examples of the past, by problems such as chart (map) and board maneuvers, and by fleet and field exercises. While the military profession can afford to neglect none of them, such tests can never be conclusive. This fact, however, far from justifying resort to any other procedure, emphasizes the necessity for utilization of the scientific method in order to arrive at conclusions which are as exact as possible. An exact result is, of course, the aim of all scientific research, but exactitude necessarily depends on the establishment of correct relationships among facts which have so far come to light. Consequently, there is great variation in the degree of accuracy which actually characterizes the several sciences. If it be maintained that only those studies which have resulted in exact conclusions may properly be regarded as sciences, then it can hardly be said that many sciences, now regarded as such, exist; for the findings of medicine, biology, chemistry, and even physics are continually being revised in the light of new data.