In this short book Captain Liddell Hart has concentrated his learning in the history of modern warfare and his reflections upon its tendencies. The result is a book which will challenge contemporary theory and practice, and which has a poitical as well as a military relevance to our desings for the future. The author divides its subject into two parts. In the first, he describes the development of modern warfare in terms of the tools of war, from the growth of fire-power in the Napoleonic wars to the evolution of the tank. He corrects the impression which was formed in 1940 that the tank gives superiority always to the attack; on the one hand anti-tank technique has been evolving, and on the other hand the tank has proved its usefulness in defence. From mechanized warfare on the ground he turns to consider the value and limitations of air power: the prevailing use of which, in his views, leads to gradual attrition rather than to rapid decisions. Lastly he discusses the effect which the flying bomb and the rocket, as part of long range artillery warfare, may exert upon war in the future. In the second part of the book, Captain Liddell Hart deals with the purposes of modern war. He reviews, with masterly brevity, the history of warfare from the Middle Ages, and the various restrictions upon warfare acknowledged in feudal times. Unlimited warfare established itself with the wars of the French Revolution; another landmark was the American Civil War, which the author considers to have been in many ways the prototype of the modern 'total war'. He shows how these tendencies became accepted in military theory by the general misinterpretation of the work of Clausewitz, and were reinforced both by mechanical inventions and political and social causes. And the 'total war' is not only bad in itself, because of its destructiveness, but is bad because it produces the wrong kind of peace. Total war, in the author's words, is 'the combination of an unlimited aim, with an unlimited method'. He hopes for a 'revival of reason, sufficient to produce self-control in war, if not the abolition of war'.