“We have only to kick in the front door,” Adolf Hitler said, predicting a swift victory in Russia, “and the whole rotten Russian edifice will come tumbling down.” Events turned out more complicated than that, as German progress was halted near Moscow in 1941 by the bitter Russian winter, and then reversed in Stalingrad by spring of 1942. The German army was in retreat, but hardly broken, all the while preparing a counterattack. Battle lines were drawn around the region of Kursk, near the city of Kharkov, with both sides gathering in an unprecedented number of tanks.

On this day, July 13, in 1943, a German panzer corps, supported by artillery and bombers, were met at Porkhorovka by an attacking Russian tank army, with similar backups, commencing the largest tank battle in history, with some 1,500 tanks involved in all.

The German army endured heavy losses in the day’s operations, and the Russian army even more so, with all but one unit standing at a third of their strength. But it was Germany’s battle to lose: they could not achieve the strategic breakthrough needed. At Kursk as a whole Germany lost 300,000 men and 600 tanks. Russia at least three times that number, but the Russians had a deeper pool of reinforcements.