There are many opportunities to avert the war. One of the earliest is the election of 1912. Given the chain of events between the archduke's death and the actual beginning of the war there are a whole host of places where the war could have been averted. As bizarre as it sounds there were points during the Great War itself that if not for nationalism could have stopped the bloodbath preventing the treaty that result in Hitler coming to power.[1][2]
After the Great War the 14 points actually going through and working, actually enforcing the Treaty of Versailles, Czech refusing the terms of Munich, killing Hitler, or numerous points in the 1920s are other options.
The Pacific War is harder. Ending the Chinese Civil War would most likely require as much resources as WWII itself. A slightly easier solution is to change the relationship with Japan or try to put a different faction in power.
"It is even conceivable that a faction could come to power that would see that in the short term, at least, Japan’s safest course lay in becoming a regional power allied with the United States rather than a global power opposed to it. Ironically, a Japan that chose to align itself with the West might be given the opportunity to intervene in and dominate China a decade later, with the Nationalist forces collapsing and Mao about to take power."
Notes[]
Frank Capra's Prelude to War provides some other points but effectively boils down to a League of Nations more willing 'to go to war over some mud huts in Manchuria' or willing to go to war against Italy when the invasion of Ethiopia started (1935).
Extra History's World War I: The Seminal Tragedy series (The Concert of Europe, One Fateful Day in June, The July Crisis, The Final Act, and Lies) shows just how in some places if just one thing had gone different after the assassination the war still might have never happened .
References[]
- Weird War II pg 6