Anglo-Soviet Treaty of 1942
The Anglo-Soviet Treaty, formally the "Twenty-Year Mutual Assistance Agreement Between the United Kingdom and the Union of Soviet Socialist Republics", established a military and political alliance between the Soviet Union and the British Empire. == Background == The Treaty followed on from the Anglo-Soviet Agreement of July 1941 that they would assist each other in fighting Germany and not seek a separate peace.
Source: Wikipedia — Anglo-Soviet Treaty of 1942 (CC BY-SA 4.0)