There are two ways to produce a book about the second world war. The first is to look through some existing books and recompile what has already been done. The second, and much more difficult, is what Rees did: conduct original research, interview survivors and create an original narrative.
Rees takes the reader from the events of 1940 and the decision by Hitler to invade the Soviet Union through the final victory in 1945. Through interviews and archival research - much of it only coming to light since the collapse of the Soviet Union in 1992 - Rees builds a picture of two armies that were lead by men whose contempt for human life was total.
The greatest strength of the book as a historical narrative is that it reminds the reader that when a decision was made, the consequences could not be foretold. Many armchair generals will tell you that such-and-such was "obvious" from the start: Rees never does. Indeed many times he analyses decisions and shows how, at least in the mind of the person taking them, a view we find utterly fantastic would have been considered quite reasonable.
One thing that made the conflict infamous was the way that Soviet political prisoners were used to fight the Germans. Groups of several hundred prisoners would be told to run at a forest so that troops could spot where the Germsn were hiding and attack. Naturally most of the prisoners would be killed: but it is symptomatic of the way that the Sovient union behaved that this was considered normal practice.
More troubling and something rarely done in books of this type, are the stories of survival and extraordinary courage of ordinary people. The terror came not just from an occupier, but Soviet partisans and other fighters seeking independence from Soviet rule. One caption was very moving: in describing how the Germans would only feed captured Soviet civilians who might be useful, there is photograph of a boy, about five years old. It states that he almost certainly starved to death.
This book was written at an opportune moment. There were still survivors who could bear witness to events without fear of the Soviet authorities for the first time. Archives of material, both Soviet and German records captured by the Soviets in 1945, were newly available to Western researchers.
Whilst an uncomfortable read, this is an excellent, nuanced, history of the period. The ultimate sadness though is that the voices of the victims of this terrible conflict, the civilians caught in the middle, will never be heard.