Central to Mazower's analysis of what he calls "Hitler's Empire", the countries that were occupied both during World War Two and the areas that were taken under German authority before the war began, is the way that the Nazi state's racialised politics shaped their approach. As he explains, this was very different to how "normal" war progressed:
In short, wartime Germanization constituted the single most forceful and ambitious attempt at nationalizing people and terrority in Europe's history. It explains why the Nazi conception of occupation involved something far more permanent, wrenching and destructive than the temporary abeyance of sovereignty mandated by liberal international law, and it contributed more than any other single factor to the increasingly violent transformation of life in the Reich itself and to the rise of the SS - the motor of Germanization - as its major political and military institution. Things, as Mazower says, "might have been different". In several places, such as the invasion of the Western areas of the USSR, the German army was welcomed. But the Nazi leadership never saw the occupied terroritories as places of allies. Almost immediately they became places which were to be reshaped according to Nazi fantasies of greater Germany. Poles and Ukrainians were moved, deported and killed to make way for German settlers, settlers that could never arrive in the numbers required. The mass and systematic killing of the Jewish population began as an attempt to deal with the Germanization of entire regions by the export of Jewish populations from areas destined to be settled by Aryans from Germany.
This also shaped the way that "ordinary" German soldiers viewed their enemies. As Mazower explains, the "[German] soldier's image of the Red Army was hopelessly, and confusingly, racialized. Sometimes it was the Jews whose pernicious influence was held responsible, but often... it was also 'Mopngols', 'Tatars' or other representatives of the 'Asiatic' hordes from whom the Nazis believed they were saving Europe."  This helps understand the brutal nature of war on the Eastern front and the response of the Red Army in turn. The fact that millions of Russian POWs died in horrific conditions has its roots in the perception of the soldiers as sub-human and the complete lack of preparation by Germany to deal with the captured men.
While the war devastated the European economy, in the short term, the German occupation of Europe did much to assist the Reich's war effort, at least in the short term. One key aspect to this was in the way that workers were brought in from both the East and the West to free up men for fighting. Foreign workers, Mazower says, went from three to 19 percent of the German labour force. In some parts of the occupied areas, despite wealth and resources flowing back to Germany, the economies did remarkably well (in the Protectorate of Bohemia-Moravia unemployment vanished and wages kept pace with inflation). Other countries did less well out of the unequal relationship. By 1943 for instance, half the French workforce was working for the German war effort and a third of national income went to Germany.
But the experience of "capitalist cooperation" in the west, was very different to the "colonial extraction" demanded in the East. There mass murder and plunder were the order of the day. Hitler's dream of the East as a breadbasket for Germany was a dismal failure, despite harsh attempts to extract everything that the regime could from countries like the UKraine and Poland. The food shortages were offset in part by imports from France and the West, but the ultimate reality was food queues in the Reich. Though Mazower notes  that food supplies in Germany were probably not as bad as in World War One, at least until the final year of the war.
The mass killing of workers and farmers in systematically undermined Hitler's ability to fight. As Mazowyer concludes  "Germany could have racial purity or imperial domination, but it could not have both."
There is much else in this detailed book. The author analyses the origins and nature of the various resistance movements, and the differing experience of Nazi occupation in countries as diverse as France, Belgium, Norway and Greece, Romania and Poland". It's worth noting that resistance was not always automatic, developing over time and sometimes vanishing in the face of repression. In Poland for instance, following the defeat of the rear-guard resistance against German invasion, resistance vanished, to reappear later. Part of the motivation for this, as one Polish General explained was an awareness that what had been done to the Jews and groups like Gypsies, would soon happen to them as Hitler's vision of a cleansed Eastern Europe free was recolonised by German settlers. The Poles "saw 'an atrocious picture of their own destiny' in what had been done to the Jews. Warsaw's sanitary officer, Wilhelm Hagen, actually lost his job when he sent Hitler a letter protesting at plans to treat 70,000 of the 200,000 Poles facing resettlement - old people and children - 'in the same manner as the Jews'."
Mazower also discusses the nature of Italian fascism, considered to be "humanitarian" by some, but he argues that this was in the context of a fascist regime aware that the war was ending and keen not to dirty themselves with allegations of genocide in the future. "[T]here can be little doubt that Italy's diplomats and generals saw perfectly strong and self-interested political reasons for doing what they could to chart their own course on Europe's Jewish Question."
Mazower's book is not one that simply concentrates on one aspect of World War Two in Europe. He draws out the way that Nazi ideology shaped the experience of war and occupation in a completely unique way. This provoked all sorts of responses, from resistance to collaboration, responses that were in turn shaped by the historic experience of different countries and peoples. As Mazower's final chapter shows, that experience continues to have an impact around the world. As a result I highly recommend this book to those trying to comprehend the origins of the contemporary world.
Cobb - The Resistance: The French Fight Against the Nazis
Gluckstein - A People's History of the Second World War
Neitzel & Welzer - Soldaten: On Fighting, Killing and Dying
Moorhouse - Berlin at War