Stalin’s own reaction [to the invasion] was interesting. He first broadcast to the people on July 4. My mother, who was a teenager in Moscow at the time, has told me that his appeal to “brothers and sisters” caused panic. Things were far worse, the Russians reasoned, than anyone had told them if the old tyrant saw them as his brothers and sisters.
Anyone interested in the opening campaign, where the Germans inflicted such disastrous initial defeats on the Red Army, should read David Glantz’s excellent book Stumbling Colossus: The Red Army on the Eve of World War. For the history of the entire war, I would suggest When Titans Clashed: How the Red Army Stopped Hitler by David M. Glantz and Jonathan M. House. I think the best site on the Russo-German war of 1941-45 is the incredible Russian Battlefield, especially the section of “soldiers’ memoirs.”