When invading Axis forces descended into the sewers of Stalingrad to move about the city unimpeded, the Soviets sent their own troops underground to stop them. The bitter fighting that took place there marked the beginning of the RattenKrieg, or “Rats’ War.” The confined spaces and narrow sewer tunnels became a hellish battlefield, unlike any before seen in the history of warfare. The claustrophobic environment was perfect for traps and ambushes, and every squad knew that death could be waiting for them around the next corner.