On June 22, 1941, the Third Reich launched its ill-fated invasion of Russia. It was pestilential in scale; more than three million Axis soldiers swarmed Russia’s borders in a matter of hours, overwhelming Soviet defenses. Hitler regarded the peoples of the Soviet Union to be a subhuman rabble against whom victory was inevitable. But the supposed Untermensch turned out to be ferocious opponents, hardened by decades of deprivation and fueled by an unbending love of country. Among those supercharged patriots were eight hundred thousand women who volunteered for frontline action, in roles such as snipers, machine gunners, and tank drivers....