Before deciding which battle best represents the turning point, it’s important to look at the strategic situation faced by the Axis (and in particular by Germany), starting in early 1939.
It has been argued that Germany lost the war when it attacked Poland. However, various plans had been made or discussed in the mid-‘30s to get the Western democracies to join the Soviet Union in ganging up on Germany. Those plans fell through not because of any hesitation on the Western democracies’ part, but because Stalin regarded both Germany and the Western democracies as enemies. He wanted a long war between those two sides–a war that would bleed both sides dry. Then the Red Army would move in to pick up the pieces.
In 1939, the combined British/French military production exceeded Germany’s; with plans underway to further expand the former source of military production. Moreover, Britain and France could draw upon the extensive resources of their colonies, and could import weapons from the United States; while Germany could do neither. Even before German tanks crossed the Polish border, Germany was in a position of strategic weakness, and had been largely isolated diplomatically by Western leaders who (in most cases) strongly preferred Soviet communism to Nazism. The French prime minister of the time–Daladier–had participated in a coalition government with the French communist party. FDR liked, looked up to, and wanted to form a long-term alliance with Joseph Stalin. Had Germany not invaded Poland, various Western politicians would have sought other pretexts for war with it. Had they failed, it’s very possible the Soviet Union would have invaded once Stalin had become convinced that his invasion would succeed, and that the hoped-for war between the Western democracies and Germany would not occur. Everything that happened from August of 1939 onward represented an ultimately unsuccessful attempt by Germany to escape that position of strategic weakness, and to secure itself against the dual threat of the Western democracies and the Red Army.
In 1940, Germany produced 11,000 military aircraft, compared to 15,000 for Britain. The U.S. shipped large numbers of aircraft and aircraft engines to Britain. It had been agreed that, over the course of the next few years, the U.S. would expand its military aircraft production to a staggering 72,000 planes per year; with half being sent to Britain for use against Germany. Even though the U.S. was still technically at peace in 1940, its industrial strength was increasingly being brought to bear against Germany.
In 1940, Hitler did not have the industrial capacity or access to raw materials or labor he required to match the Anglo-American war effort being waged against Germany. One of the reasons for his invasion of the Soviet Union was to acquire these things; thereby allowing him to match the Western democracies’ aircraft production over the long haul. Victory over the Soviet Union would also secure Germany’s eastern front before any serious invasion of its western front could be launched.
However, Germany’s population in 1939 was 69 million; as compared to 169 million for the Soviets. That gave the Red Army a staggering advantage in manpower. Moreover, the Soviets’ military production exceeded that of Germany’s by a factor of between three and four for most major land categories in 1942. The Soviets also produced nearly twice as many military aircraft as Germany did that year. The overwhelming advantage the Soviets had in manpower, together with their equally overwhelming edge in military production, were why Germany could not hope to win a long war against the Soviets.
It is also worth noting that Britain had imposed a food blockade on Germany, which created a severe food shortage. German occupation policy in the Soviet Union was harsh because its lack of available food meant it had no choice but to starve many millions of people. There just wasn’t food to feed everyone. People in conquered Soviet territories were among the millions starved. That meant that the Germans could not be seen as liberators, but were rather cast in the role of hostile invaders who must be resisted at all costs.
In 1941, Japanese industrial capacity was only a tenth that of the U.S. The U.S. produced 48,000 military aircraft in 1942, compared to just 9,000 for Japan.
The phrase “turning point” implies that there was some time in the war before which the Axis had the advantage, and after which the Allies had the edge. At least from a strategic perspective, there was no turning point in WWII. Germany was at a significant disadvantage before the war began, and that disadvantage remained throughout the war’s duration. It experienced some remarkable tactical victories during that time; particularly its conquest of France and the western parts of the Soviet Union. But those tactical victories were never enough to create strategic parity with the Allies. Nor could Japan’s early victories in the Pacific offset the U.S.'s massive advantage in industrial capacity.
It could be pointed out that early in the war, the Axis had a brief window of tactical opportunity: a time for it to win victories before the overwhelming Allied strategic advantages could be fully brought to bear. On Germany’s western front, its string of such victories ended with the Battle of Britain. On its eastern front, they (mostly) ended with the battle of Moscow. And in the Pacific, Japan’s string of early victories ended at Midway.
It would have been very difficult or impossible for Germany to have launched a serious invasion of Britain. It lacked the transport capacity and surface fleet to do so. Moreover, with Britain producing more and better aircraft than Germany in 1940, Germany’s window of opportunity to invade was clearly very brief. While a successful invasion of Britain would have been extremely beneficial to the Axis war effort, British victory in that battle was never in much doubt.
The Battle of Moscow was similar. Germany lacked access to much oil. Therefore, its supply lines could not primarily rely on trucks. Instead, it would use coal-powered locomotives to carry supplies most of the way to where they were needed, and horses to transport them the rest of the way. The need for rail significantly slowed the German advance, so that Soviet rail lines could be converted to the German gauge, and so that the rails could be repaired or replaced. Germany had enough oil and military trucks to provide some motorized supply for its troops; and that helped speed the invasion of the Soviet Union. But by the Battle of Moscow, its fragile supply lines had been stretched to the limit. Its soldiers lacked the food, medical supplies, ammunition, and winter uniforms they required. Germany’s failure at the Battle of Moscow was a function of the strategic weakness it had experienced even before the war began. That battle also reflected the Soviets’ enormous manpower reserves and overall military strength.
