Old movie with a bomb that freezes

I remember an old movie from my youth (possibly black and white movie or maybe also tv-series) about a conflict where one side is threatening to fire a bomb/canon with a projectile that can freeze the other side. In the last minute, the firing is prevented as the canon backfires into the chamber and freezes everybody behind the closed door. I simply cannot find it on any movie site. It could be from germany, but I’m not sure.