The German aggression against Poland on 1 September 1939 marked the beginning of the Second World War, the bloodiest armed conflict in the history of mankind. Hostilities ended in Europe on 8 May 1945 and in the Far East on 2 September 1945.

Germany, after Adolf Hitler’s rise to power in 1933, gradually began to violate the provisions of the 1919 Treaty of Versailles imposing several restrictions, especially in terms of its armed forces. The lack of any real reaction from the leaders of the European states to those measures strengthened Hitler’s conviction that he would succeed in changing the balance of power imposed after the First World War by the method of accomplished facts. The result was the remilitarisation of the Rhineland, the Anschluss of Austria, as well as the seizure of Czechoslovakia.

The next state claimed by Germany was Poland, but confident of the security guarantees provided by France and the United Kingdom, it firmly refused to meet the demands formulated by Hitler. The geopolitical situation of the Polish state was difficult, as it was practically bordered by the Third German Reich on three directions since March 1939. However, it deteriorated even more radically after the signing of the non-aggression treaty between Germany and Soviet Russia in Moscow on 23 August 1939, commonly referred to as the Molotov-Ribbentrop Pact. In a secret protocol attached to it, the two totalitarian states agreed on the future division of Central and Eastern Europe, including, above all, Poland.

The implementation of those plans took place less than ten days later, because on 1 September 1939 Germany attacked Poland. The start of the war is considered to be the shelling of the Polish outpost at Westerplatte in Gdansk by the German battleship ‘Schleswig-Holstein’, which began at 4.45 a.m. The Polish army had to retreat despite the heroic resistance against the more numerous German forces and the failure of France and Britain to provide assistance, despite their Allied commitments. The situation became hopeless after the Soviet army crossed the Polish border on 17 September 1939.