In January 1558, Russian regiments, by order of Ivan the Terrible, crossed the Russian-Livonian border. For four years, from 1558 to 1561, the Baltics were engulfed in the flames of a war that soon became known as the Livonian War (this war, in turn, became part of a longer conflict that can be called the War of the Livonian Succession, which lasted de facto from 1555 to 1595 G.). As a result of the actions of the Russian troops, the “sick man” of North-Eastern Europe, the Livonian “confederation”, consisting of the Livonian Order, the Archbishopric of Riga and a number of other, smaller possessions, was defeated, disintegrated and divided between powerful and greedy neighbors. The history of this war, despite its significance for the subsequent history of not only Russia and the Baltic states, but also the states that intervened in the conflict - Poland, Lithuania, Sweden, Denmark - has been studied extremely poorly, especially by domestic historiography. This short work, written using both domestic and foreign sources and literature, fills this gap. It provides a brief military-historical (and partly diplomatic) outline of this conflict, which will be useful not only to historians, but also to everyone who is interested in Russian history, and especially the history of Russian military affairs of the 16th century.