Hells, they barely cared if their soldiers were armed or fed.

Not only that, but there were just millions of people who genuinely were fleeing communism, even if it meant surrendering while you were winning.

That being said, you are right, the other time I remember victorious forces surrendering was in the Battle of Inchon where the 300,000 strong Chinese Army forces were enduring -40 C temperatures in summer clothing, and were occasionally encountered by retreating US Marines. Those soldiers, many horribly frostbit and starving, tried surrendering, and sometimes the Marines could take them, but most of the time they couldn't. God only knows how many died. China still keeps the losses a secret. The devastation could range anywhere between 40%-80% losses. Once the seasons changed, fresh soldiers (still wearing summer gear) could replace the hundreds of thousands that died.