Why is the German Invasion of Poland usually marked as the beginning of the Second World War?

Scaeva

Ad Honorem
Oct 2012
5,628
#52
Well, let's have a look at that claim on a map.

*snipped maps*
The maps are misleading in that many of the shaded areas for the Second World War were European colonial possessions that on the whole were far from any fighting. Up to 1941 the Seven Years War remained a much more global affair than the Allied war effort against Germany, with ground combat operations in Europe, North America, South America, West Africa, and India.

Every war has to have a start date, the history books require it. So anyone trying to put forward another date - justify it. How is that the start of World War 2?

Does anyone here actually believe that the Sino-Japanese war led directly to the invasion of Poland?
The invasion of Poland likewise had zero impact on events in Asia, where a war that would later become the Asian and Pacific theaters of the Second World War had long before been underway.

How about the Italian invasion of Ethiopia? What is the direct link between that and the declaration of war by Germany on Russia?
The Second-Italo Ethiopian War was a separate conflict from the Second World War, being concluded before the latter began. It is certainly linked to the Second World War however, in that it expanded Italian East Africa and Italian colonial ambitions would directly impact the course of the Second World War.

In that it could be compared to the Japanese victories in the first Sino-Japanese War or the Russo-Japanese War.

So you can hardly claim these events started World War 2 when they obviously didn't. They may have been the writing on the wall, shadows of the events if you like, but they were not the event themselves.

However, on 1st September 1939 we have an event that unquestioningly leads to World War 2.
1 September 1939 has a similar problem to that which you're criticizing the other dates for - it had no impact whatsoever on what would later become the other half of the Second World War. The war that would later become the Asian and Pacific theaters of the Second World War had been raging for years before Poland was invaded. Furthermore it in no way linked what were entirely separate wars on opposite ends of the globe.

The link between those two separate conflicts would not come until the United States went to war with both Germany and Japan and the British Empire entered the war against Japan. Those events were a direct consequence of the Japanese attack on Pearl Harbor, not the German invasion of Poland. Without a Japanese attack on the United States it is quite possible that the Sino-Japanese War and war against Germany and Italy would have remained separate conflicts.

The German invasion of Poland leads to Anglo-French involvement, which leads to the involvement of the colonial powers, which leads to the defeat of France which leads to Italy joining the war, which leads to the war In North Africa (not to mention the battles across Africa and the Middle East against Vichy forces) and the Battle of the Atlantic, which leads to American involvement (the American navy was fighting against U-boats before December 1941).
Sorry, but this is a stretch. The United States was certainly sympathetic to the United Kingdom and often skirted the boundary of neutrality prior to 7 December 1941, but it was not at war with Germany prior to Pearl Harbor. War between the United States and Germany was not a consequence of the invasion of Poland, it was a consequence of the Japanese attack on Pearl Harbor. Without a Japanese attack on Pearl Harbor there would not have been German and Italian declarations of war against the United States.

All Pearl harbour did was, like Barbarossa, open a new front in an on-going war that was already 2 years old at the time.
This is flat out incorrect.

The consequences of Pearl Harbor were that two entirely separate conflicts on opposite ends of the globe were unified into a single, global war. That did not happen with either the German invasions of Poland or the Soviet Union. It could have happened if Japan decided to join Germany in invading the Soviet Union, but Strike South triumphed over Strike North, and Pearl Harbor became the event that linked those two separate conflicts.

For clarification I'm personally not in favor of using 7 December 1941 as the start date of the Second World War, as war had been raging for years in Europe and Asia before the Japanese attack on Pearl Harbor. It is however a better candidate than the start date for the invasion of Poland, which was not the first battle of what would later become the Second World War, and did not in any way tie the Sino-Japanese War into a single global conflict. I favor using 7 July 1937, or the Marco Polo Bridge Incident as the beginning of the Second World War.
 
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Naomasa298

Forum Staff
Apr 2010
35,030
T'Republic of Yorkshire
#53
Were all those countries at war with Germany in September 1939? Yes. Did all those countries actually start mobilizing armed forces to fight Germany? Yes. How were those countries not involved then?
Did all of those countries actively participate in combat with Germany in September 1939? No.
 
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Maki

Ad Honorem
Jan 2017
3,385
Republika Srpska
#54
Did all of those countries actively participate in combat with Germany in September 1939? No.
And that somehow makes them not at war with Germany? They were preparing for actively participating in combat with Germany. By that same logic, the US and Germany were not at war before November 1942.
 

Naomasa298

Forum Staff
Apr 2010
35,030
T'Republic of Yorkshire
#56
And that somehow makes them not at war with Germany? They were preparing for actively participating in combat with Germany. By that same logic, the US and Germany were not at war before November 1942.
It certainly makes them not active participants in a supposed "world war".

Yeah, they weren't. So maybe 1942 should be the start of "World War" 2.
 

Maki

Ad Honorem
Jan 2017
3,385
Republika Srpska
#57
Not active participants, but preparing to be. And of course, they were officially at war.
 

Naomasa298

Forum Staff
Apr 2010
35,030
T'Republic of Yorkshire
#58
Not active participants, but preparing to be. And of course, they were officially at war.
Even if they were, why is 1st of September considered the start then? Britain and France didn't declare war until the 3rd, and Canada not until the 10th.

And Germany was preparing to invade Poland in August. Why not then as a start date?

And be all that as it may, if the US and Japan had not got involved, would it have been considered a World War? I doubt it.
 

Maki

Ad Honorem
Jan 2017
3,385
Republika Srpska
#59
Even if they were, why is 1st of September considered the start then? Britain and France didn't declare war until the 3rd, and Canada not until the 10th.
Same reason why World War I's accepted start date is July 28th. The invasion of Poland was the event that directly caused the other countries to declare war, so it would be wrong to exclude its beginning from the war.

And Germany was preparing to invade Poland in August. Why not then as a start date?
Because Germany was not at war with Poland in August. There was no war, passive or active, in August.
 
Dec 2014
428
Wales
#60
The invasion of Poland likewise had zero impact on events in Asia, where a war that would later become the Asian and Pacific theaters of the Second World War had long before been underway.
I disagree. The reason for the expansion of WW2 and the attack on Pearl Harbour had nothing to do with the Pacific, but was all about the countries of SE Asia. It was about taking the wealth of the Dutch and British colonies, making Japan independent of outside resources. The attack on Pearl was an attempt to cripple the main threat Japan faced while undertaking this expansion. As a result, The Sino-Japanese war had nothing to do with the Asian/Pacific theatre, except in the vaguest terms. It was an entirely separate war and would in all likelihood have progressed much like the Japanese invasion of Manchurian six years before had WW2 not broken out in Europe. China was brought into WW2 because of the Japanese attack on the Allies, and the Sino-Japanese war became a part of the greater WW2, not the other way around.

If you wish to claim the Sino-Japanese war is the start of WW2 you must show a direct link between it and the war in Europe, in the same way I showed a cause and effect (the involvement of those same colonial nations in the war) for the war in Europe spreading to the Far East. Since there can be no links from east to west, and since the war in Europe was 2 years old at the time of Pearl Harbour, then the most you can claim is that the European war and the Pacific war were, for the entirety of the war, two separate wars involving the same countries, but with no link between them.

The Second-Italo Ethiopian War was a separate conflict from the Second World War, being concluded before the latter began. It is certainly linked to the Second World War however, in that it expanded Italian East Africa and Italian colonial ambitions would directly impact the course of the Second World War.

In that it could be compared to the Japanese victories in the first Sino-Japanese War or the Russo-Japanese War.
Agreed. It helped lay the groundwork for the war, was even a driving factor – but it was not the start of the war.

1 September 1939 has a similar problem to that which you're criticizing the other dates for - it had no impact whatsoever on what would later become the other half of the Second World War. The war that would later become the Asian and Pacific theaters of the Second World War had been raging for years before Poland was invaded. Furthermore it in no way linked what were entirely separate wars on opposite ends of the globe.
Again, that is incorrect. Firstly, it was not an Asian/Pacific war, it was a Chinese war, taking place entirely in China. It did not involve any nation in Asia other than Japan and China. For 5 years this is all the war was. On 7th December japan attacks the allies and in 4 days the entirety of SE Asia, America and most European nations are all at war. Can you truly see any links between these two events, links that took 5 years to mature? At the same time you have to ignore the fact most of these nations had been at war for years already, and treat that as an entirely separate war.

The link between those two separate conflicts would not come until the United States went to war with both Germany and Japan and the British Empire entered the war against Japan. Those events were a direct consequence of the Japanese attack on Pearl Harbor, not the German invasion of Poland. Without a Japanese attack on the United States it is quite possible that the Sino-Japanese War and war against Germany and Italy would have remained separate conflicts.
I mostly agree with this, but the point is that I am making is that the Japanese attack on Pearl Harbor WAS a direct result of the war in Europe, itself a direct result of the German invasion of Poland, as Japan sought to take advantage of the power vacuum in SE Asia the war in Europe had created with the German defeat of the colonial powers.

Sorry, but this is a stretch. The United States was certainly sympathetic to the United Kingdom and often skirted the boundary of neutrality prior to 7 December 1941, but it was not at war with Germany prior to Pearl Harbor. War between the United States and Germany was not a consequence of the invasion of Poland, it was a consequence of the Japanese attack on Pearl Harbor. Without a Japanese attack on Pearl Harbor there would not have been German and Italian declarations of war against the United States.
Tell that to the USS Greer (DD-145), when she became the first American warship to fire on a U-boat on 11th September 1941 after being fired upon by U 652.

USS Greer (DD-145) - Wikipedia

Lading FDR to issue what became known as his "shoot-on-sight" order: that Nazi submarines' "very presence in any waters which America deems vital to its defense constitutes an attack. In the waters which we deem necessary for our defense, American naval vessels and American planes will no longer wait until Axis submarines lurking under the water, or Axis raiders on the surface of the sea, strike their deadly blow—first."

Or to the USS Reuben James (DD-245), sunk with 100 casualties after being attacked by the U552 on October 31st 1941

USS Reuben James (DD-245) - Wikipedia

The war in the Atlantic was a shooting war long before December 7th, and it usually accepted that one of the main reasons Hitler declared war on America was because of the open conflict between American forces and German Submarines in 1941. Indeed, the German declaration of war specifically states this, saying:

On September 11, 1941, the President of the United States publicly declared that he had ordered the American Navy and Air Force to shoot on sight at any German war vessel. In his speech of October 27, 1941, he once more expressly affirmed that this order was in force. Acting under this order, vessels of the American Navy, since early September 1941, have systematically attacked German naval forces. Thus, American destroyers, as for instance the Greer, the Kearney and the Reuben James, have opened fire on German submarines according to plan. The Secretary of the American Navy, Mr. Knox, himself confirmed that-American destroyers attacked German submarines.

German declaration of war against the United States - Wikipedia

This is flat out incorrect.

The consequences of Pearl Harbor were that two entirely separate conflicts on opposite ends of the globe were unified into a single, global war. That did not happen with either the German invasions of Poland or the Soviet Union. It could have happened if Japan decided to join Germany in invading the Soviet Union, but Strike South triumphed over Strike North, and Pearl Harbor became the event that linked those two separate conflicts.

For clarification I'm personally not in favor of using 7 December 1941 as the start date of the Second World War, as war had been raging for years in Europe and Asia before the Japanese attack on Pearl Harbor. It is however a better candidate than the start date for the invasion of Poland, which was not the first battle of what would later become the Second World War, and did not in any way tie the Sino-Japanese War into a single global conflict. I favor using 7 July 1937, or the Marco Polo Bridge Incident as the beginning of the Second World War.
And this is a personal opinion, so suggesting so emphatically it is ‘flat-out incorrect’, in opposition to the accepted historical timeline of every major historian for the last 70 years needs something more than a ‘I favour’. The political and economic situation surrounding the Sino-Japanese war unarguably had an affect on the war in the Pacific, but it did not cause it. Such an event as the attack on Pearl and the subsequent Asian/Pacific war would never have happened in 1938/39 - while a war between Japan and Russia did occur (see the Battle of Khalkin Gol) - and the idea of Japan opposing the combined might of America, the British Empire and the French and Dutch colonial powers, even with a successful attack on Pearl is ridiculous. Only in 1941, after the destruction of 2 of those nations and the desperate struggle for survival of a third was such an attack remotely feasible – and none of that has anything to do with the Sino-japanese war.
 
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