The military danger in the world increased after the establishment of the Nazi dictatorship in Germany. The leadership of the USSR made active attempts to create the system of collective security in Europe, but potential allies — Great Britain and France — showed hesitation and weakness, tried to ward off the threat from their countries using the policy of appeasement of the aggressor. By August 1939, it became obvious that the efforts of the Soviet leadership did not bring results, in these conditions the USSR had to conclude non-aggression pact with Germany.

World War II (September 1, 1939 — September 3, 1945) was unleashed by Nazi Germany, which was then joined by fascist Italy and militaristic Japan.

On June 22, 1941, the Great Patriotic War began; it became nationwide for the population of the USSR. In confrontation with the enemy, the front and rear united — the country turned into the single military camp, the large-scale people’s war unfolded in the territories temporarily occupied by the Nazis. The SovietGerman front was the main one in World War II.

Almost three-quarters of all enemy troops, the bulk of its military equipment and weapons, acted against the Red Army; it was here that the enemy lost almost 80 % of manpower and equipment.

The heroic efforts of the Soviet people, defended the Fatherland, strengthened the position of the USSR in the international arena and created the conditions for the successful solution of three main tasks by the Soviet diplomacy: the creation of anti-Hitler coalition, opening of the Second Front and the solution of the issue of the post-war world order. They were discussed, as necessary, at meetings of the three powers heads of government of the anti-Hitler coalition: Tehran (November 28 — December 1, 1943), Yalta (February 4–11, 1945) and Potsdam (July 17 — August 2, 1945) conferences.

The Nuremberg Trials (November 20, 1945 — October 1, 1946) summed up the results of World War II and became the first international trial of Nazi ideology in world history.