What single action (or non action) had the biggest effect on the outcome of World War Two?

Question

Is it possible to highlight a place and time, a significant battle, or a technological breakthrough that affected the outcome of World War Two more than anything else? For example, the German invasion of Russia, the Japanese attack on Pearl Harbour, the reduction of Luftwaffe bombing over the UK, the development of Radar? I know this is an open ended question and there is unlikely to be a "right" answer but I would be interested to hear any theories.

Answer 1

There are several:-

+ The breaking of both the German and Japanese codes is possibly one of the most significant factors:-
- in the Battle of the Atlantic it enabled U-Boats to be tracked down and destroyed and gave important insights into German intentions and order of battle which enabled meagre resources to be concentrated where they were needed.
- in the Pacific it enabled US forces to anticipate Japanese intentions such as at the pivotal Battle of Midway

+ The invention and development of RADAR
- This helped save Britain in 1940 in the Battle of Britain, which in turn prevented the German invasion and thus provided the springboard for the eventual liberation of Europe. If Britain had been invaded the decisive battles in Europe such as the Normandy Landings and the Battle of the Bulge would not have been possible.
- Radar enabled the Allies to develop the Radar Proximity Fuse which meant that anti-aircraft fire was much more effective. This and search radar is what protected the US Navy during the Pacific War - and without which they may well have been defeated in the Marianas, Leyte Gulf and Okinawa. Without the capture of Pacific Islands such as the Marianas even weapons such as the atomic bomb would have been useless as no aircraft would have had the range to reach Japan.

+ Perhaps the biggest mistake on the part of the Germans was their invasion of Russia and Hitler's refusal to attempt to capture Moscow until it was too late in the year. This led inevitably to the German's defeat at Stalingrad and later at Kursk. Germany's complete underestimation of the severity of the Russian winter and the manpower resources available to Russia made defeat all but inevitable from the outset.

+ The other major German mistake was their failure to recognise fully that Britain could only be defeated by starvation and isolation by way of defeating the convoys. The number of U-boats produced was simply too small to allow this at the time when shipping was at its most vulnerable - before the introduction of proper escort groups including Escort Carriers equipped with HFDF (direction finding equipment to detect U boats from their radio transmissions) and escort destroyers and corvettes armed with forward-throwing depth charge equipment such as Squid and Hedgehog. This is in stark contrast to the very effective anti-shipping campaign operated by US submarines against Japan (once difficulties with the Mk XIII torpedo had been overcome) and the total failure of Japan to protect her shipping which was vital to her very survival. If Britain had been isolated by U Boat blockade then the vast production resources of the USA would have been neutralised because it would have been impossible to bring it to bear on the point of battle - the European coastline and the Russian Front via the Arctic Convoys. Churchill himself described the Battle of the Atlantic as the one that gave him the most concern.

+ The biggest mistake on the part of the Japanese was to attack the US in the first place. Many have argued that Japanese defeat was all but inevitable from December 7 1941 given the huge disparity in industrial capacity and lack of readily available resources, particularly oil.

+ Air power played a significant role in all aspects of WWII and interestingly both the Germans and the Japanese followed mistaken paths in this respect:-
- they both failed to develop any significant strategic capability... their tactical use of aircraft was superb for winning battles against weakened or unprepared oponents but could not in themselves ensure strategic victory
- both Japan and Germany failed in the training of new aircrew. Both kept their frontline pilots in action until they were killed or injured whilst the Allies rested their crews between tours, these rest periods being frequently used to impart knowledge to trainee crews and permitted them to return to the frontline as experienced leaders. This provided a continual supply of well-trained and combat-ready crews whilst for both Germany and Japan the well trained crews that started the war had all but gone by the end with no like-for-like replacements.

Answer 2

Stalingrad by far and away.

I say this because Stalingrad was the key to Caspian petroleum. Had the Nazis taken Stalingrad and managed to turn the Caspian oilfields towards the benefit of their empire, I sincerely doubt even the full force of the rest of the industrialized nations of the world would not have been able to dislodge the Nazis from Europe.

What many people tend to forget about the nature of fighting in the Second World War was that even though everyone had weapons powered by internal combustion engines, all three of the Axis powers were forced into using those weapons on a very tight fuel budget while the Allies had no such constraints. In the case of the Nazis, this manifested itself best in their choice of more common weapons like the u-boat, light armor, light lift/ unarmoured bombers, "buzz bombs" or the V series rockets, and the conversion of their fighters into defensive weapons. These were all high yield, low cost weapons as compared to what most of the Allies chose to use which over the course of the war ended up limiting the Nazi's tactical abilities.

Add to this the fact that these choices virtually eliminated any logistical use of petroleum anywhere else. There were hardly any trucks to move supplies or men. There were no Jeeps to move Nazi officers around. There were few machines available to move artillery etc. This was all done by horse and coal fired train which put them at a whole new level of risk. Tracks could be easily destroyed on land and with somewhat more of a challenge from the air. One bullet has a lot more stopping power on a horse than a truck etc.

In short it was a huge disadvantage for them.... but had they made the Caspian that could have all disappeared.

Imagine what difference it would have made if the armies in Russia didn't require their supplies to come by wagon for hundreds of miles? What if those winter clothes, food, and ordinance came by truck or even out of a heavy lift plane? What would have happened if every Nazi tank the British, Canadian, American, and Free forces had met would have had twice the armour and on board ordinance? What would have happened if the Nazis could have doubled their lift capacity and kept up the Blitz indefinitely? What would have happened if they could have doubled the u-boat fleet and started running surface ships that were the calibre of the Bismarck?

Anyway, I think you see where I'm going with this. My answer is Stalingrad because the Russians stopped Hitler from getting a choice about how he could have fought the war.

Answer 3

This is the sort of question to which the answer will depend, to a certain extent, on where the one answering is from.

British are likely to mention the Battle of Britain, El Alamein, RADAR and the cracking of the Enigma code. THe Russians would go for Stalingrad. The Americans for Pearl Harbor. Americans and British are more likely than Russians to cite D-Day, as the Russians often view that as a minor distraction compared to what they were doing on the Eastern Front.

In terms of British participation, and bearing your mention of "non action" in mind, I would suggest Germany's failure to wipe out the BEF before Dunkirk. The Panzer divisions were well placed and could easily have done so, had Hitler commanded. Hitler still had the goal of an alliance with Britain somewhat in mind.
Also, the switching of the Luftwaffe bombing raids from airfields to cities. This allowed the RAF valuable time to recover and take on the Luftwaffe.

Had Germany destroyed the BEF and later the RAF, this would have cast into doubt Britain's ability to hold out, which would have made the staging of D-Day much trickier.
That said, that view places far more importance on D-Day than would be accorded by a Russian view.

Answer 4

Germany was the most powerful military force in Europe at the time BY FAR America was divided about entering the war because may believed it was "none of our business" and some, Charles Lindbergh for example actually approved of Hitler with out the Massive and protected production capacity of the United States it is very likely that Germany would have defeated both Britain and Russia. And also Japan would have conquered China and the whole of Indo China Germany had the plans and the ability to build the Atomic bomb and intercontinental bombers and missiles to attack and defeat the US if they had not been destroyed. this is NOT to DENY the bravery of the allies who did much of the fighting It can be argued that bombing cities and civilians was in fact a war crime. But war itself is a crime. Stalin and Hitler were ALLIES at the beginning, until Germany, which was Fascist anti-communist thought they could win a two front war. History is very complex your Q shows a lot of bias as well has having some valid points

Answer 5

I'm not that familiar with Europe but in the PAcific there were 3 critical battles all in 1942:

1. Coral Sea, this battle stopped Japan and put two carriers (Zuikakau and Shokaku) out of action for the next battle,
2. Midway, this battle Japan lost 4 big carriers (Akagi, Kaga, Soryu and Hiryu) along with most experienced pilots crippling Japan's Navy,
3. Guadalcanal, this battle raged for months with both sides (UA and Japan) placing enormous amounts of resorces into the battle. The US emerged the victor and Japan had lost a lot in terms of material and manpower something they were not able to overcome.

Answer 6

Mine may be an America centered view, but I'd say the most important act in WWII was the Japanese attack on Pearl Harbor, bringing the US into the war and virtually wiping out opposition to American entry into the conflict. Once American manpower and industrial might were committed to the war effort, I'd say the defeat of the Axis powers was a matter of time.

Answer 7

Since I do not believe that I can expand upon the fine answers already given, I would like to answer with two points to where non-action was decisive.
1) I believe that the biggest effect was during the Munich conference in September 29, 1938. In which the western powers yielded to Hitler. Had The western powers stood firm and sent troops into Czech that might have stopped Hitler in his tracks. Hitler had pretty well consolidated his power in Germany but the threat of another war might have jeopardized his hold on power.
2) The Treaty of Versailles, had the victorous Allied powers listened to Woodrow Wilson, and treated the United States as an Equal power then perhaps the entire war would not have happened.

Very interesting question with many very good answers.

Answer 8

Great answers. I'd have to go with Pearl Harbor for the simple reason that it ushered the U.S. into the war wholeheartedly. I'm sure the Allies knew there was no way of losing right at that moment.

Honorable mention: the Battle of Britain.

Answer 9

What a bunch of really good answers.

I'd like to add the inability of Americans to understand what was happening in Europe and their willingness to look the other way. Had the American public gotten involved, then Lend Lease would not have been necessary and Japan would have been on notice that America was ready, willing and able, to come to the aid of it's allies.

Answer 10

Two actions greatly changed the course of WWII and its outcome. 1. Japan failed to occupy Hawaii and continue on to the west coast of the US. 2. Hitler attacked Russia at the wrong time if year. His army didn't have the time to secure their objective before winter set in. If either event had been accomplished I believe the world would look a lot different today.