Other ‘What if’s:-
San Francisco, the Presidio (garrison) was built by the Spanish as a stopper against the southern expansion of the Russians from Alaska!! If there was no great USA western expansion trhen you have the possibility of Tricorn/Napoleonic Russians V Spanish with native Indians & Cossacks thrown in.
USA never buys Alaska, the guy who did it as a private purchase was ridiculed at the time. USa has a very close neighbour , the USSR !!!!
Napoleon does not sell Louisiana to the USA
The Republic of Texas does not join the USA, changes the ACW a bit. Of note some people inTexas want do withdraw from the USA NOW !!! (not long after Texas won independance from Mexico, a group of radicals decided to break away from Texas, they declared the State of ‘Freedonia’ [A name much used by the Marx brothers in their films] In reality they galloped out of one end of town when Texican cavalry arrived at the other end, but ‘what if?)
ACW Britain invades from Canada, it very nearly did happen. A Union warship stopped a British ship (that was bad enough) and removed two Confederate agents (how dare they!!) Britain objected in the strongest terms over this insult. Lincoln had the agents quietly released over the Canadian border, saying, ‘One war at a time’ but what if he hadn’t?
Fall of Constantinople. The Ottomans were about to call off their long seige, but decided for one last day of attack. On the last attack of the day they found ONE sally port that had not been shut properly. That tower fell, the next towers saw the Christian flags fall & retired. A domino effect led to the city falling. What if that door had been shut?
WW2 the German landings on Crete. One New Zealand unit, under great pressure, withdrew from a hill overlooking a crusial airfield & the Germans rushed in transport planes, but what if…?
May I recomend the book ‘The Moscow Option’ It take a fact (Upon returning from visiting his generals on the Russian front , Hitler’s plane skidded on the ice & NEARLY crashed) and twists it a bit (The plane crashes, Hitler survives but is in a comma). The High Command hush it up, I know the Nazi party not telling the truth who would ever believe that, they are then free to run the war without Hitler interfering. I will not spoil it, in case you want to read it, but I will mention a few bits:-They redeploy a chunk of the Luftwaffe during the Russian winter. So instead of just freezing in Russia, they support a Crete style invasion of Malta; Rommel gets enough supplies & men to break through the British. He crosses the Suez canal & invades Palestine (Tells his wife, in a letter, he can’t get over seeing Bethlihem in his battle orders); The SS & the Whermacht fight each other in a power struggle.