Upon the receipt of confirmed espionage of the military preparedness of the Soviet Union, German Fuhrer Adolf Hitler gave the last-minute order scrubbing his intended invasion. Knowledge of Stalin's military buildup was well known, but the exact numbers were suddenly daunting. As seen by Hitler then and later calculated upon declassified documents by state historian Mikhail Meltyukhov in his work, Stalin's Gift, Russians outnumbered the Germans and their allies 1.4-to-1 in infantry and artillery, 2.6-to-1 in aircraft, and stunningly more than 3.8-to-1 in tanks. Hitler had surprise on his side as Stalin, despite the advice of several spies who had given him the exact date of invasion, believed Hitler would hold longer than two years to the Molotov-Ribbentrop Pact and wait until he finished war with Britain. Hitler had already postponed the intended Operation Barbarossa several weeks from its initial deadline in May due to logistical problems, and now he knew certainly he was too late.
As Hitler and his staff reviewed the numbers, he knew that Germany would be unable to maintain the blitzkrieg he had used successfully against Poland and France without control of the air and against numerically superior tanks, with Russian heavy tanks even arguably superior to Panzers one-on-one. Finally Hitler realized that the Russians were simply too powerful by weight and determined that he would need new kinds of weapons to fight, redoubling his already heavy investment in research and development for rockets, atomic bombs, and more. He let continue the lie that his massing troops on the border with the Soviet Union was keeping them away from attacks by Britain and eventually recalled them for Operation Sea Lion, which had been postponed indefinitely since September, 1940.
Japanese attack on Pearl Harbor brought Britain's near-ally America into the war fully that December. With American resources turned toward the Pacific, Hitler's invasion of Britain began, which quickly turned into a quagmire of resistance and sabotage of nearly every public work. Although Hitler held Western Europe for several years, the Allied counter-attack through Africa enabled Britain to be liberated by the D-Day landing at Devon, June 6, 1944.
In early 1945, with Hitler reeling despite some Soviet support Stalin made good on his original strategy of waiting. Called the “Icebreaker” theory by exiled historian Viktor Suvorov, Russia swept in as liberators across Europe, meeting with American and British allies as they took Berlin and continued toward the Western Front, spreading as far as France and Italy. Churchill and Roosevelt encouraged Russia to relinquish their control of Europe as soon as order could be maintained, but Stalin decided to stay. As war with Japan ended with the new A-bomb, political stakes were raised with the Americans holding a powerful card, but Russia practically fresh for a fight.
War-weary President Truman decided to leave the Russians in Europe, establishing doctrine that would work just to keep the Soviets from expanding further. This, too, would prove a blunder of waiting as the Russians would use captured German scientists, now pampered celebrities outside Moscow, to surpass the atomic bomb with an H-bomb and rocketry capable of intercontinental delivery by the 1950s. An Iron Curtain fell from East France to North Italy and across the Soviet Balkans that looked to expand through the Middle East, Africa, even Latin America, and absorb Chinese Communism into the Soviet-led World Community. Any opposition to the world superpower had to be covert, such as escapes across the Swiss border and arming of Afghan guerillas, as no nation could stand against Stalin's legacy until it eventually collapsed into corruption and civil war.
In reality, Operation Barbarossa proceeded. With army strengths of more than seven million, Hitler and Stalin fought bitterly over Eastern Europe for months until the Germans were finally stopped and held by sheer numbers. Eventually, the tide would favor the Russians, who would come to take much of Eastern Europe under their influence after World War II and hold it until the wave of independence movements in 1989.