In June 1941, Nazi Germany launched an attack upon the Soviet Union. The German Reich had been building up forces along the Eastern Front for a long time, but the sudden aggression caught Soviet forces unprepared. Many troops were captured and the Germans quickly conquered territory from the Soviet states. But the Soviets reorganized, improved their communication structure, and pulled together a defense at Smolensk. Although they lost again, they critically slowed the German advance and halted their race towards Moscow. Instead, the Germans tried to lay siege at Leningrad, only to be struck themselves by insufficient supply lines and a brutal winter that claimed the lives of many soldiers. With that, the Wehrmacht withdrew and redirected its efforts towards Stalingrad. Josef Stalin refused to let them take any land "further than the Volga" in Russia, and mounted a stiff defense. Even when the Luftwaffe, the German air force, reduced the city to rubble, Soviet soldiers continued to wage war from the debris. Meanwhile, the Germans were so focused on their offensive that they let their defensive lines collapse, and in October 1941 the Soviets managed to surround and pin down the German 6th Army. Their commander refused surrender terms because he didn't want to displease Adolf Hitler, but the 6th Army's resistance inevitably collapsed in February 1942.

James explains why World War II series on Extra History won't use the swastika of Nazi Germany.

Richard "the Challenger" Cutland, ex British tankie and military specialist at Wargaming, stops by to talk about the types of tanks involved in the Battle of Kursk! Early in Operation Barbarossa, the Germans didn't expect much from their opponents. They did not know about the T-34 and KV-1 tanks, which turned out to be superior designs. The Germans deployed a special commission to study Soviet tank designs and soon introduced the Tiger, Panther, and Ferdinand tanks which Hitler believed were key to victory. The Panther in particular was now outclassing Soviet tanks, but it had giant mechanical issues and broke down frequently. The Soviets had produced a new T-43 model tank, but it was designed to tackle the old German Panzer IV and didn't measure up well to the new German tanks. So they preferred to focus on the trusty T-34 tanks, which made up in speed and numbers what they lacked in range and firepower. The Kursk region also played to the Soviets' advantage in Russia: the dust storms and mudfields hindered air support from the Luftwaffe and the advance of the Wermacht. Erich von Manstein, the German commander, decided not to advance. Instead he yielded ground to the Soviets in an attempt to lure them into overextending. He successfully caught them out at the First Battle of Kharkov, but even though the Soviets suffered heavy casualties there, it wasn't enough to make a dent in their huge army. Manstein needed to do something more drastic. Both he and the Soviets recognized that the Soviet line had a weakness where it bulged out to defend the city of Kursk, making it an obvious target for the next stage of operations.

On July 5, 1943, the long-awaited German assault began. Despite the arrival of the powerful new German tanks, the Soviets ground their advance down to a crawl thanks to the stiff fortifications they'd had time to lay in place. The Germans planned their assault for July 5, 1943 but a defector warned the Soviets and denied them the element of surprise. Even without the warning, General Zhukov had found plenty of time to fortify Kursk with layer upon layer of pillboxes, minefields, and more. He planned to bloody the Germans with this staunch defense and weaken them for later. The new German tanks, such as the Tiger, arrived only to find themselves outnumbered by numerous Soviet T-34s and ill-supported by maintenance crews who were stretched too thin by the number and variety of new tanks being deployed. General Manstein ordered his strongest tank unit to push through, targeting the small town of Oboyan, but although he made the most progress along the line of the assault, even he had not expected resistance on this scale. By the next day, the Germans had barely reached the second line of Soviet defenses, and while they hadn't been forced to retreat anywhere, they were distinctly behind schedule. Hitler needed them to win. It wouldn't win the war, but he hoped that it would force the Soviets to withdraw, leaving him free to concentrate on the Western front and the threats from the United Kingdom and the United States.

Twelve days of ferocious battle wore both sides down to the bone. Each German push was met with a Soviet counterattack in places like Ponyri and Prokhorovka, until finally the Allied invasion of Sicily forced Hitler to recall his troops. German divisions had not expected the level of resistance they met from the Soviets, and their planned advance was behind schedule. At the same time, the Soviets were concerned by the breaches in their first level of defense and by the Tiger tanks which so decisively outgunned their T-34. Fighting on the north side of the Kursk salient came to focus on the small Russian town of Ponyri, where the Germans saw an opportunity to break through and encircle the Soviet defenders. But every time they took control, the Soviets countered and took it back, until finally it became clear that they would never hold Ponyri and could only hope to divert troops from reinforcing the Soviet line elsewhere. But in the south, General Vatutin of the USSR had come up with a clever strategy: he literally buried his T-34 tanks up to the turrets, making them fortified anti-tank guns whose small profile negated the range advantage of the Tiger. His methods were extremely effective, but the Germans continued to fight forward inch by bloody inch. The Soviets needed to hold until reinforcements arrived. An attempted counterattack failed, but managed to slow the Germans, as did the sudden arrival of rainy weather that bogged down their materiel. In the midst of this, the brutal war criminals in the SS Division fought on with a ferocity best exemplified by Joachim Krüger, who once ripped off his pants to escape a smoke grenade and charged bare-assed at a Russian tank. But this wild back and forth could not continue. On July 12, 1943, the Germans sought a decisive outcome through a hard push at Prokhorovka. They did not get it, and the tides quickly turned against them. The Allies invaded Sicily, pressuring Hitler. He gave the command to withdraw the troops at Kur