"Seventy years after the departure of the international Voluntatrios participants in the Civil War of 1936-1939, there are still very relevant aspects to be analysed. Historiography has long unraveled the general framework of foreign intervention in the conflict, but still remains to cover some flanks that remain with many questions. One of them is the participation of Europeans from Central and Eastern Europe, a region very unknown and yet of great importance to Republican Spain. This text explains the causes that influenced the decision to fight in such a distant confrontation with their places of origin, the ideological affiliation, the number and contribution of the volunteers in the "War for Freedom", as well as the peculiar contribution of Each nationality, according to its own political and cultural tradition. The monograph also provides information on scarce known archival sources that offer a very complete overview of the characteristics of these brigades, whose problems did not end with the farewell of their troops in the year 1938 "