The book is devoted to the history of the Ukrainian army in the XIV-XVI centuries. On the examples of military campaigns and battles, the traditions of Ukrainian armed formations, their tactics and combat techniques in the confrontation with the nomadic hordes of the Steppe, the Principality of Moscow and the German Order are analyzed. The role of Ukrainian regiments in the formation and development of the Grand Duchy of Lithuania is indicated, the relationship between the organization of the army and the political structure of the Gediminovich state, the continuity of the existence of the Ukrainian armed forces as a component of the development of military affairs in Europe is shown.