This was also a form of "The winner takes it all" as has been the case in history countless times before.
The Soviet Red army fought Germans and as Germans retreated and ran towards the end of their war effort Red army troops closed in from all countries to the east of Germany (Poland, Czech republic, the Baltics etc.)
While allied forces like US, UK, closed from west, the Red army and west met near Torgau along the Elbe river, a historical moment in the war as Germany was at that point effectively cut in two and for all practical purposes defeated. It was just that after the war ended unlike the Americans the Soviets did not leave but stayed in the parts that they had previously fought Germans, after all this was the original plan between Hitler and Stalin known famously as "Molotov - Ribbentrop pact" in a bit changed way. This pact is notorious for it's secret protocol that basically divided Europe between Stalin and Hitler, just that Hitler made mistakes tried to grab too much and got killed so in the end Stalin got more of his part.
https://en.wikipedia.org/wiki/Molotov–Ribbentrop_Pact
https://en.wikipedia.org/wiki/Elbe_Day