Loudspeakers in the frozen rubble played a ticking clock and announced that a German soldier died in Russia every seven seconds. This episode treats the Battle of Stalingrad as a biography of a catastrophe, beginning with Case Blue’s real objective, the Caucasus oil fields, and the flank-protection mission that became an obsession once Hitler split Army Group South to capture a city bearing Stalin’s name. We look at the week-long traffic jam when the 4th Panzer Army was redirected across the path of the 1st Panzer Army, and how that delay gave the Soviets time to realize Moscow was not the target.

From there we descend into Rattenkrieg, the rat war, where Luftwaffe bombing created a rubble fortress that neutralized German armor, General Chuikov ordered his troops to hug the enemy within grenade range, and the main railway station changed hands 13 times in three days. We cover fish hooks soldered to grenades, field mice chewing tank wiring, surgeons amputating with carpenter’s saws, and the stress that gave Paulus a facial tic and left Chuikov’s hands bandaged. The episode closes with the maskirovka that hid a million men on open steppe, Operation Uranus smashing through the Romanian flanks, Hitler’s refusal to allow a breakout, Goering’s impossible airlift promise, and Paulus’s surrender in February 1943 as the first German field army ever captured.

• Why a mechanized Blitzkrieg army was fatally dependent on petroleum
• How wire nets over windows and fish-hook grenades show real-time lethal innovation
• Why the under-equipped Romanian, Italian and Hungarian flank armies were the Soviet target
• The Sword of Stalingrad presented by Churchill and the deterrent effect on Turkey and Japan
• How hundreds of soldiers’ bodies are still recovered from the soil beneath the modern city every year