The Point of divergence is that Joseph Stalin 's purges of his own military ( 1936 – 1938 ) were far more costly than in reality ; in this version , Georgy Zhukov and Ivan Koniev were also killed . In addition , Operation Barbarossa began in May , 1941 , rather than June as in real history , giving Nazi Germany more time to fully exploit the surprise attack on the disorganized Red Army
purges of his own military
Great Purge
Counting Up, Counting Down