Huge numbers of prisoners were being taken by the Germans in the encirclement battles, where whole armies were captured. The Wehrmacht was totally unprepared to handle them all, and a very high proportion of those captured in the early battles would die by the end of the year - from starvation, sickness, maltreatment, exhaustion from the long marches, and exposure to the elements.
For some, the end was much swifter - perhaps, with hindsight, mercifully swift. Erich Stahl was fighting with the Waffen-SS at this time, and his brutally honest memoir gives plenty of examples of what was going on at this time:
