The author is Timothy Snyder and the subtitle is The Holocaust as History and Warning. Here is one bit:
The Germans had come to understand that pogroms were not an effective way to eliminate Jews, but that the production of lawlessness was an appropriate way to find murderers who could be recruited for organized actions. Within weeks they grasped that people liberated from Soviet rule could be drawn into violence for psychological, material, and political reasons.
In per capita terms more Jews from Estonia died than from any other country at the time. As of 1944 there were still three-quarters of a million Jews in Hungary and ultimately more than half of Hungary’s Jews survived the Second World War, even though Hungary was both a German ally and it was later invaded by Germany. More generally:
Jews who were citizens of Germany’s allies lived or died according to certain general rules. Jews who maintained their prewar citizenship usually lived, and those who did not usually died…Jews from territories that changed hands were usually murdered. Jews almost never survived if they remained on territories where the Soviet Union had been exercising power when German or Romanian forces arrived…In all, about seven hundred thousand Jews who were citizens of Germany’s allies were killed. Yet a higher number survived. This is a dramatic contrast to the lands where the state was destroyed, where almost all Jews were killed.
Recommended, interesting throughout, and gripping throughout, including the discussions of agricultural productivity and of Hitler as a non-nationalist who saw race as the primary category of human existence. It’s not easy to write an original and readable book on the Holocaust these days, but Snyder seems to have done it. You can read some reviews here.