The new monograph continues the author's research of hostilities at the Russian Theater. In 1915, 10 million people participated in them, and losses exceeded 6 million, including 1.1 million dead and 2.1 million prisoners. They were not replenished, which had a decisive impact on the further course of the war and the strategies of the opponents. For the first time in historiography, the author analyzed in detail all operations on the Russian front on archival sources of all parties newly introduced into scientific circulation. He not only established the number and categories of losses, their accounting, the impact on the conduct of hostilities and planning, identified the reasons. Summary data are tabulated in detail up to the joints and individual parts. The book can become a historiographic bridge between the studies of domestic and foreign historians, uniting the memory of the war of the peoples of Europe.