The book presents two works of the same name by outstanding Russian military theorists and historians of the first half of the 20th century: Andrei Evgenievich Snesarev (1865-1937) and Anton Antonovich Kersnovsky (1907-1944). The authors present their understanding of the nature of wars, the causes of their occurrence, forms and properties. Each of them sees the history of the development of military affairs in his own way and analyzes the pre-revolutionary domestic military system.