ENThe threat to the independence of Lithuania, Latvia and Estonia was caused as soon as they declared it. Possible aggression by Soviet Russia, which later became the Soviet Union, and Germany, posed a danger to all three countries. It was reasonable that the Baltic countries discussed the possibility of getting together. Lithuania, Latvia and Estonia considered various options to form some kind of union. Such a union, often referred to as the Baltic Union or Baltic Entente, was formed only in 1934. The military factor is one of the components of any effective union. In this particular case it should be understood as the threat of invasion by external military forces, the internal demand and opportunities of the Baltic countries to confront this threat together and deter aggressors. However, the Baltic Entente failed to have this kind of military alliance usual for such type of agreements. The greatest need to form the Baltic Union, where the main subject of the contract could become the military factor, was in 1919–1920. Unfortunately, through no fault of its own, Lithuania was the weak link that prevented the formation of such a union. Bermondtists threatened to suppress the statehood of Latvia in its infancy and only Estonia provided support. However, it was small-scale support. For Lithuania between Germany supporting Bermondtists and basic Bermondtist forces intersected by the railway artery controlled by the Bermondtists and German Armed Forces was like being between a hammer and an anvil. At the same time, Lithuania was threatened by the aggressive policy of Poland. The idea of the general state offered by Poland was a real threat not only to the statehood of Lithuania, but also to the identity of the Lithuanian nation. Relations between Poland and Lithuania, the active instigator policy of Germany and the Soviet Union, hindered the formation of the Baltic Union for a long time.Mistakenly believing that the Entente Powers, and later – the League of Nations, was the guarantor of a peaceful co-existence in Europe significantly decreased the importance of the military factor. In addition, the military power of potential aggressors was poor: the German armed forces were limited by the Versailles Treaty and did not pose a threat, and the Soviet Armed Forces were trying to escape from post-revolutionary poverty, Bolshevik chaos, and being technically backward. Thus, Baltic military cooperation failed to take place in practice. In 1933, when the National Socialists took power in Germany, the situation changed, and the arms race began. The Baltic countries became the subject of debates of the major countries on security guarantees. Before the Munich Agreement, international security mechanisms were relied on too much and the possibilities of a military Baltic Union had not been discussed at the highest political level. When the Soviet Union was forced to sign the mutual aid agreements and accept contingents of Soviet troops, the formation of a military alliance was prevented. Lithuania, Latvia and Estonia neither tried to standardise their weapons nor plan joint military actions and the possibility of joint military command. Analysis of actions during the Winter War and the Second World War in the Baltic countries suggested that it was possible to resist the Soviet occupation by military force. Although there was great advantage in numbers, joint forces in the Baltic countries had the opportunity of organised resistance and retreat into the territory of a third country, not involved in hostilities, allowing governments to be preserved and protecting part of the population from repression. Military power was the only political instrument that was not used in order to avoid the occupation or reduce its impact.