In June 1944, the Red Army captured the German Army Group Center. This was called Operation Bagration. 185 Soviet divisions with 2.3 million soldiers surrounded and captured or killed the 800,000 members of Army Group Center.
A month later some of the German POWs were transported to Moscow to display to the Soviet people.
Here is a Soviet film of the parade:
The parade was followed by trucks ceremoniously washing the German filth from the streets. The POWs were then transported off to work camps.