I'm confused about how supply works in WiTE2 (another refugee from Paradox). Supposedly I pocket Stalinrad, and Soviet player left a supply depot in Stalinrad to make a stand, what happened next?

For example if I'm very incompetent German player and stucked at pre-war border at T16.So no VP, will there be any punishment event that affect me?

What can I do on with the ground force with extra more VP?