The question of whether there is a general, universal theory for the conduct of war has long preoccupied military thinkers, army personnel and students of conflict. Warfare has been radically transformed throughout history, under the influence of technological change. But is there anything enduring that can be determined about it, taught in military schools and applied in practice?
Azar Gat offers a fresh look at the relationship between politics and war, examining the meanings of "victory," offence and defense, and the significance and role of concepts like the 'principles of war' and military 'doctrine'. He analyses the successive military innovations of modernity, including the advent of nuclear weapons and the ongoing cyber and robotics revolutions of our own times. He also explains why guerrilla warfare and terrorism have grown increasingly important, and where they are heading.
With China and Russia posing a growing challenge to the global order today, Gat asks if war is truly in our nature--or if it is, in fact, declining. This is a vital text for all students of war, whether in academia, in the military or among the public at large.
If you want a short introduction into many of the major themes that the author has written about, this is the best one I have read. I find Gat to be a very concise and clear writer, and generally find his arguments persuasive. This book is a great distillation of the many military themes he has written about elsewhere.
Here he explicitly asks if there is a universal military theory, and answers mostly in the negative (if you have read Gat's other books, many of these themes are echoes of his earlier work). While there are some elements that appear universal, they tend to be so abstract that they do not help in concrete situations without further doctrine/context.
If you want a more extended discussion, Gat's recent entry on Clausewitz ("The Clausewitz Myth") and his classic work "War in Human Civilization" will answer in more detail some questions about the nature of war and humanity's propensity to warfare.