As the poet Tyuchev observed, you cannot understand Russia using common sense. The Battle of Stalingrad cannot be understood through standard analysis. The purely military study of a battle of such magnitude does not manage to convey the reality of the battlefield, just as Hitler's maps in the "Wolf's Lair" in Rastenburg failed to isolate him in a fictional world, far from the sufferings of his soldiers.

The idea behind writing this book is to reveal, within the context of conventional historical narrative, the experiences of the troops on both sides, aided by a wide range of new information primarily from Russian archives. The variety of sources plays a decisive role in describing the unprecedented nature of the battle and the consequences it had on all those who were trapped within it with almost no hope of escape.

Among the sources are war diaries, reports from military chaplains, personal experiences, letters, interrogations of Germans and other prisoners by the NKVD, personal diaries, and interviews with participants. One of the richest sources from the central archive of the Russian Ministry of Defense in Podolsk consists of the very detailed reports sent daily from the Stalingrad Front to the head of the Political Department of the Red Army in Moscow, Aleksandr Shcherbakov.

These reports describe not only heroic deeds but also "unusual incidents" (a euphemism used by the commissars for treacherous behavior), such as desertions, defections to the opposing camp, cowardice, incompetence, self-inflicted injuries, "anti-Soviet discussions," and even drunkenness. The Soviet authorities executed about 13,500 of their soldiers in Stalingrad for such "incidents"—more than an entire division.

The main challenge, I soon realized, was to attempt to juxtapose the authentic self-sacrifice of so many Red Army soldiers against the extremely violent coercion exercised by the special units of the NKVD (which very soon fell under the jurisdiction of the counterintelligence SMERSH) against those who hesitated to fight.