In the summer of 1942, the Germans launched Case Blue, a strategic offensive into the Caucasus, a region rich in oil, birthplace of Stalin, and gateway to Iran and the Middle East, where the Germans could obtain more oil, cut off a vital corridor for Lend-Lease supplies to the Soviets, threaten the British Empire, and even perhaps link up with the Japanese (then advancing in Burma toward India). It was a pivotal moment of World War II, which history remembers primarily for the titanic clash at Stalingrad during the fall and early winter of 1942-43, but less well understood is the series of summer operations that led to and shaped that turning-point battle. In Prelude to Stalingrad, Igor Sdvizhkov reconstructs the fighting in the northern sector of the Case Blue offensive, near the city of Voronezh. Using German documents as well as previously classified Soviet sources, Sdvizhkov zooms in on the nine days of see-saw fighting-involving tens of thousands of men and hundreds of tanks and guns on both sides-that threatened to derail the German offensive north of Stalingrad. In response to the withdrawals and mass surrenders on the Eastern Front during the war's early months a year before, Stalin ordered that no ground be given up, that his armies fight instead of pulling back, ensuring that the fighting would be brutal. Ultimately unsuccessful in denying the Germans a bridgehead on the Don River, the Red Army inflicted heavy losses, eroding the Wehrmacht's fighting power before it even reached Stalingrad.