On this day 17 September 1939 the #USSR joined #Nazi Third Reich in its attack on #Poland, marking the start of World War 2.[^1]

Many isolated locations in Poland continued defense well until end of September, like Warsaw,[^2] but on 22 September the Nazis and Soviets met in Brest (today’s #Belarus) and concluded the occupation with a friendly handshake.

The Third Reich and Soviet Union remained close allies for the next two years, with the Soviets providing critical logistics back end to the Nazi Germany, supplying it with millions of tons of fuel, steel and other resources[^3] in bypass of international economic sanctions, while Germany continued the conquer of #France and the rest of Europe.

In June 1941 Germany wholeheartedly paid back its ally by sending all the bombs manufactured with Soviet steel back on the Soviet towns during “Operation Barbarossa”, but that’s another story 😏

[^1]: https://en.wikipedia.org/wiki/Soviet_invasion_of_Poland

[^2]: https://en.wikipedia.org/wiki/Siege_of_Warsaw_%281939%29

[^3]: https://en.wikipedia.org/wiki/German%E2%80%93Soviet_Commercial_Agreement_(1940)