This question has been debated for decades and no one issue can answer it in full. There are many arguments and theories about what caused the second world war but no one conclusion has ever been agreed upon. The war to end all wars was a brutal slaughter of men and the only thing agreed upon was that it should never happen again.
Upon looking at the information provided I would have rashly theorized that the Second World War stemmed from the Treaty of Versailles and the fall of the League of Nations in 1933 upon further research and following up on various leads I have however come to a different conclusion, but this is only one of many I have found along my journey of WWII. This is a very loose theory based on many aspects on the road to war which I hope to look at in much further depth at a later date.
The Treaty itself was extremely harsh and very unforgiving taking into account nothing of what would happen to the German civilians when this monstrous document came into force. The Financial implications left Germany with nothing and the country fell to ruin. Families suffered. Politicians still ate, they still went home to comfortable beds at night with their families surrounding them and their maids serving them but civilians who had done nothing except try and survive the war themselves suffered massively. Some lost homes; many had already lost their men and their sons and were already suffering the same grief that any Britain, French or Italian citizen suffered. To add to this the financial penalties along with the restriction of growth (border restrictions) was naive and arrogant. Through ages past it has been proven time and time again that when people suffer together they stand the most defiant. (The French revolution is only one example of this). Removing military troops and destroying or removing arms was at least in some form acceptable, asking for remuneration for damages was acceptable, returning territories conquered was even acceptable but the Treaty of Versailles took liberties and those liberties were taken from the already suffering German citizens. If the treaty was meant to deter politicians and hierarchy from further war it failed dismally. With the somewhat half hearted assistance from the League of Nations all it succeeded in doing was giving Germany time to recuperate, rebuild and wait for a saviour to come along and save them. Hitler was that saviour they would turn to two decades later. Hitler, and this is no compliment, was a genius. He used his charisma and manipulated the people, he manipulated the politicians (and assassinated anyone he could not manipulate) He manoeuvred himself into a position where the people needed him and he had their blessing to end the war that should have rightfully been won by them some 20 years previously.
We return to the League of Nations. In light of the information provided it would seem that The league of Nations managed their administration to a limited degree throughout the 1920’s however we are lead to believe things started falling apart in 1930’s due to the rise of Japan Germany and Italy as 3 new major powers. Each challenged the League of Nations in some form and consequently left leaving the League of Nations with even less backing than they had previously had. After following a lead on the Treaty of Versailles however it is discovered that in 1919 the Germans logged their objections to the treaty Britain considered renegotiating the Treaty however France nor America would not entertain this idea in any form. At this point the league of Nations had not officially been formed as yet.
In 1922 Germany failed to deliver a supply of wood and were ruthlessly invaded by France in order to retrieve it. There was no wood to retrieve. Under the terms of the Treaty this was viable however The League of Nations was now formed and this should have been avoided at all costs. The terms of the treaty had not taken into account land mass, growth and time-scales It was impossible to supply wood when there were not enough trees to supply from. Shortly after this America stepped forward and bailed Germany out of a great deal of debt with a loan. This helped to get Germany back on its feet although it was a slow process it did help. America continued to aid Germany over the coming years keeping them above water.
At this point Hitler would have been around the age of 33. After joining the German army in 1914 he had already received 6 medals for bravery as a runner in the trenches during the great war. With or without the League of Nations Hitler was already on his path to starting world war two. At the age of 30 his journey had just begun and although he faltered as he tried to find his feet it was still the start of his journey when in 1919 he joined the National socialist German workers party (NSDAP), this was quickly corrupted to Nazi. Although this party was very small it was to be the beginning of Hitler's career in warfare. Again I state that at this point the League of Nations was not officially formed as yet and the treaty of Versailles now hung over Hitler's head like a dark cloud. This, along with various other unhealthy hatreds, fuelled Hitler to drive forward to his end goal, leading the Germans back into their former glory, no matter what the cost.
Between 1924 and 1929 Hitler spent time in prison re-thinking his strategy into politics and re-integrating into the NSDAP on his release. Between this time frame it could be said that under normal circumstances Hitler would not have succeeded as his party were consistently failing to gain more seats. Something happened at this point however that would forever change the face of history. Wall Street crashed and America pulled in all her investments across Europe, including Germany. Germany was now back on her knees with nowhere to turn.
Now return to the year 1919 for a moment when the Germans first logged their objections to the Treaty of Versailles and neither France nor America would renegotiate the terms. There had been no League of nations then and up until 1929 they had done little to affect any outcome on a war. They had Indeed allowed their members to invade one another without reprimand or consequence and they had up until this point kept arms limited throughout the nations involved with the league but up until 1926 Germany had not been involved with the league so between 1920 and 1926 the league of Nations were still relatively inconsequential to the oncoming war with Germany. there is no way they could have foreseen a 30 year old runner in the German army with a passion for war and an unhealthy hatred of Jews amounting to a leader hell bent on giving his country back what the Treaty of Versailles had taken from them.
In 1929 Wall street crashed and took everyone with it. Germany was left looking for their saviour and Hitler was almost ready to take up that mantle. In 1930 Hitler began his campaign to have the Nazi’s elected. He staged speeches, mesmerized crowds and created a unity among the German citizens that had not been seen since before the Great War. When the elections were over the NSDAP were the second largest political party in Germany. Overnight they had accomplished the impossible and became one of the biggest influences in Germany from a party that barely held onto 7 seats to a party that now held 107. I would add at this point that Germany had joined the league of nations in 1926 and that this would be a pinnacle point where the League of Nations should have taken notice. this was not an easy accomplishment even when the events leading to it were as devastating as the wall street crash. This deed had never been accomplished in such an overnight and astoundingly massive significance in votes. This was never addressed in this manner however, they had viewed them as one of the three rising powers but Germany was about to become much more than this although no-one seemed to notice.
In 1931 The League of Nations found themselves being tested over the Manchurian crisis. when Japan, a major new power, attacked China the league of Nations had opportunity to deal with this. Without the backing however they could only sit idle and watch. At this point it is noteworthy to mention that although they had dealt with a few minor disagreements in the early 20’s they had never dealt with anything on this scale before. through previous lack of retribution or consequence and through lack of resolution between many smaller nations previously the league of Nations had backed itself into a corner and had no way to deal with the blatant disregard for the common purpose of the league. Collective Security. Japan blatantly ignored this while other nations sat in amongst the league observing that Japan was suffering no consequence.
In 1932 Hitler ran for president in Germany which should have drawn attention. His speeches were not clouded with niceties towards other nations. His message was becoming clearer. He wanted to return Germany to its former glory, “tear up the Treaty of Versailles and end war reparations” (www. The History place.com) and if the league of nations had taken note they would have known there was only one way to achieve that. The 1932 election campaign did not put Hitler in the president's seat however it did unnerve many other German politicians as the NSDAP numbers seemed to be soaring in the public’s eye. It did not however seem to upset the League of Nations who continued to ignore the signs of an oncoming war if Hitler did succeed. 1932 was to be a long year of politics and backstabbing in Germany which at least delayed the war for one more year, however the final results of 1932 were to cause Hitler to take the position of chancellor of Germany in January of 1933.
This now brought Hitler into direct contact with the league of nations so he too could sit and observe how things were dealt with from their perspective. He was indeed there when Japan decided to leave the League of Nations due to a unanimous vote against their invasion of Manchuria. They were seeking further space for their growing population and received no reprimand or solution to this problem. The vote told Japan everything it needed to know. The League of Nations was of no benefit to them so the resigned from the League as Hitler watched. with the resignation of Japan without consequence, there would be nothing stopping Hitler form leaving. Not only were they limited in arms by the Treaty of Versailles but the disarmament limits stopped all members building up any form of security and Hitler was aware of it all. In effect The League of nations had spoon fed him information on each nation's military supplies. Shortly after Japan resigned from the league of Nations, Germany followed. The League of Nations was now proving themselves to be inadequate for the task expected of them and collective security was failing. Nothing was being done to protect the smaller country’s being invaded, nothing had been done in the past. The remaining members fought on regardless trying to maintain their ideal but unrealistic concept of collective security.
In 1934 it should have been crystal clear to anyone watching that something was wrong with the German government. Operation hummingbird (the night of the long knives) finally put Hitler into a position where he could officially declare himself the leader of Germany. Many opposition political members were “set up” and shot by the Gestapo. It is said that possibly hundreds died in this “purge” but it left Hitler with complete and absolute power. With this absolute power and his charismatic appeal to the millions now, Hitler set about rebuilding the German military, the fleets, the air force and the arms needed for the war he had waited for nearly 14 years now. In 1939 he would achieve that war.
1935 brought on the Abyssinia invasion in which Italy were not reprimanded in any way for invading. At this stage It is perfectly clear that Germany now has a plan. Japan has invaded twice and is likely to invade again. The statistics show that the League of Nations has or could have stopped many smaller wars if they had not sat in “Appeasement”. it is clear to see that either another governing body was needed to help support the League or they needed to use harsher methods to deal with members who had disregarded the leagues purpose. I would also add at this point that the League of nations in the instance of world war 2 were inconsequential. World war 2 would have happened with or without them in formation. Even though I state earlier that they should have sat up and taken notice when Hitler started to rise, if they had, there would have been nothing they could have done except allow the members to build more arms in readiness for the war to come.
The war happened because even before the League of Nations was devised ,an unfair and inhuman set of expectations set down in the Treaty of Versailles. The war happened because the world did not take the opportunity to renegotiate the terms of the treaty in 1919 when the option was offered. The war happened because innocent German civilians were made to suffer greatly for something they could not really control. It happened because those same people who had suffered the same as anyone in the war who had lost someone needed someone to turn to, someone to save them. The war happened because in 1914 Hitler took his hatred of Jews and his passion for war and ran the trenches happily, even gleefully. . There was another war because Hitler manipulated, manoeuvred and assassinated his way into absolute power. The war happened because when the great crash happened in 1929, Hitler even manipulated that to his advantage, drawing in millions to his beliefs. Vengeance was the cause of World war two or was it just the inconsiderate demands the world made on the Germans that caused the 50 million deaths of world war two.