Adolf Hitler, an Austrian of origin, a German National Socialist, was the perfect person to act as a catalyst for the great conflict. In 1933 he came to power in Germany on the wave of feelings of revanchism for the unjustly imposed Treaty of Versailles. Although extremely anti-communist in its rhetoric, for a short time he had become a useful ally, as expressed in the non-aggression pact signed in Moscow on 23 August 1939, which contains a secret clause defining the division of the sphere of influence in Central Europe. It was mainly thanks to Soviet guarantees of aid that Hitler decided to start the war with Poland in September 1939, which soon turned into a world conflict, long-awaited in the Kremlin.
Vyacheslav Molotov signs a pact with the Third Reich, later called the Ribbentrop-Molotov Pact.