The full-scale Russian invasion of Ukraine on 24 the second year was a surprise to many people, for others a logical consequence of the concentration of Russian troops and the designation by the Russian Federation (three days earlier) of the “independence” of the pseudo-states of Donetsk and Luhansk People's Republics. The course of the fighting amazed even more observers, including experienced analysts. What lessons can and even should be drawn from past hostilities?