World War II: Temperatures around Moscow drop to −12 °C (10 °F) as the Soviet Union launches ski troops for the first time against the freezing German forces near the city.

The Soviet Union, officially the Union of Soviet Socialist Republics (USSR), was a transcontinental country that spanned much of Eurasia from its formation in 1922 until its dissolution in 1991. It was the world's third-most populous country, the largest by area, and bordered twelve other…