This is another short book, but provides an excellent background on Barbarossa, as well as a concise explanation of the first year of the campaign. It includes a phase by phase analysis of the Nazi plan and practice for genocide against the inhabitants of Soviet Russia.
Some of what happened was planned, some wasn’t, but the next effect was that millions of the Soviet soldiers and civilians that found themselves behind German lines were dead before the next spring. Some were killed in combat or because they were Jews or other groups that Germans intended to kill anyway, but most died from starvation and exposure as a result of the failure of the German high command to provide for their survival. Nor was this mere negligence – Germany never intended to provide for the survival of POWs in large numbers, and deliberately took food and winter clothing from civilians to support its home front and the troops on the Eastern Front.
Horrible story, but efficiently told.