Maybe it was the day that most the Red Army found itself in another country and consequently sold off its surplus arms to the rest of the world so they could kill each other instead?
This day was really meant to be a navy day.
It happened so after the new soviet republic just born, and as far as I know, in early twenty century Germany began a war company against a yound comunistic state. Can`t remeber where, but soviet army, which was formed from mostly workers and peasant defeated outnumbered foe`s army, and defended the state. And from that day they started to celebrate it.