Bloodlands a while back and have been processing, or, more accurately, attempting to process, the content ever since. Snyder paints a vivid account of the scale of the civilian and non-combatant slaughter in the territories between Germany and Russia that occurred between 1933 and 1945.
Is it the heaviest book ever written in English? Given the scope and scale of the material I think it might be. We have the benefit of contemporary firsthand accounts, and the numbers are overwhelming beyond human comprehension.
When you read that Stalin killed over 750,000 people in his great purges of 1937 and 1938, how do you wrap your head around that? If you read that Stalin starved over three million (!!) Ukrainians to death as part of his collectivization strategy in 1932/33 then what does that mean? Do you get caught up in the details of death by starvation, which are so harrowing I do not even want to reproduce them here? Or do you imagine what it would be like if all of San Jose (1.0 million), Dallas (1.3 million) and San Diego (1.4 million) were starved to death? What would that look like?
Once you get past Stalin's successful mass murders - if you can - then you come to Hitler, whose army and their compatriots killed even more civilians and POWs in a shorter span of time. The accounts of Hitler's/Germany's victims are every bit as horrible as anything that Stalin and his teams could design.
Though a difficult read, this is essential history, and I cannot recommend it highly enough.