Final answer:
Order 227, issued during the Battle of Stalingrad, forbade Soviet troops from retreating or falling back, encapsulated by the directive 'Not one step backwards!'
Step-by-step explanation:
Order 227 issued by Joseph Stalin in July 1942, during the Battle of Stalingrad, dictated that Soviet troops could not retreat or take a single step backwards. This order was meant to prevent any Soviet forces from retreating or falling back in the face of the German advance. It was famously summarized with the phrase "Not one step backwards!" at a time when the morale was extremely low and the ability of the Soviet Union to continue the war was in question. Order 227 reflected desperation and aimed to instill discipline and resolve within the Red Army, even at the expense of large numbers of Soviet soldiers' lives.