This song is one of the first official songs of the Red Army, written in 1920, in the time when victory was already visible, but bloody battles still raged in the East and South. This song also remained on of the most popular military songs till the break up of the Soviet Union.
The clip is not mine; I got it from Vladlena1917. It is made up from segments of Soviet cartoons, and when I saw it I just had to write subtitles.
Note the two headed eagle at the beginning. This symbol of Russian empire had always been a polar opposite of the Soviet Union, but if you watch my "New Dawn" video till the end, you'll see the same bird with a red star on its back. Try to figure out what it implies.