For instance back in September 1862 right before the Civil War battle of Antietam, a Union officer by chance, found a piece of paper on the ground that detailed General Lee's strategy to temporary divide his army while crossing the river which would cause considerable delays.
That is 100% true.
Antietam ended up a bloody affair and even though ended as a draw, that politician Lincoln would treat it as a glorious Union victory and from there announce the Emancipation Proclamation.
In the 1950s alternative history novel 'Bring The Jubilee' by Ward Moore, the premise was one of Lee's staffers retrieved the paper before the Union got their hands on Lee's formation strategy and Antietam resulted in a Confederate victory that ultimately won them the war by the end of 1862.
Turtledove then tried in the 2nd half of the book to depict what a post-war Confederacy and America would be like politically and economically..
He would also write a form of alternate history where enemies become allies in the face of a greater foe.
There's one novel he wrote where the US and CSA fought a 2nd war against one another in the 1880s then ultimately allied when Britain invaded both territories, and a WWII novel called "In the Balance" where Hitler, Churchill, Stalin and FDR became allies to ward off an extra-terrestrial threat..
These books aren't for everyone especially those who like things as they are..
Of course this Did already happen during WWII when the US and the Soviets fought on the same side...
And when Britain and France allied themselves in the very early 1900s after centuries of constant warfare, united over an increasing fear of pre-WWI Germany's military, naval and territorial expansion..
And its happening now.. Between the US and Iran..
And yes.. Israel..
"U.S. aerospace companies are seeking permission to sell airliner parts to Iran for the first time in three decades, in a key test of the temporary relief on sanctions given under talks to curtail Iran's nuclear activities.
At least two leading manufacturers, Boeing and engine maker General Electric have applied for export licenses in a six-month window agreed by Iran and six world powers in November..
A senior Iranian official told Reuters in November that Iran could require between 250 and 400 jets if and when sanctions are lifted completely."
"[A] court in Athens has told The Telegraph that parts appearing on an American list of forbidden military-grade materials had been shipped from Israel on two occasions, apparently destined for Iran.
The seized items comprised spare parts for military aircraft: a constant speed drive designed for the F-4 Phantom jet, and a voltage output sensor used in the F-14 Tomcat.
The parts were confiscated by Greece’s financial crimes squad and were being sent to the US for investigation, court officials said...
Israeli arms dealers twice tried to send spare parts for fighter planes to Iran, The Telegraph has established, flouting an international arms embargo and openly contradicting the bitter enmity between the Jewish state and the Islamic regime...
The shipments - one in Dec 2012 and the other last April (2013) were sent by courier from the Israeli town of Binyamina-Givat Ada, near Haifa, via a company in Greece. The firm was later established to be a ghost company. Its contact number was said to belong to a British national in the Greek city of Thessaloniki, who could not be traced. "
Seems pretty odd, yes?
Why would sworn enemies be engaged in this manner.. besides greed?
Illicit Israeli arms shipments to Iran first came to the public attention, during the 1986 Iran-Contra scandal, when it emerged that Israel was acting as a conduit to send weapons to from the US to Iran in exchange for its help in winning the release of American hostages held in Lebanon.
Then in 1998, an Israeli court sentenced Nahum Manbar, a businessman and former decorated soldier, to 16 years in prison after he was convicted of secretly selling Iran equipment to make chemical weapons.
"Iran has stepped up support on the ground for President Bashar al-Assad, providing elite teams to gather intelligence and train troops, sources with knowledge of military movements say...
The Syrian leader has drawn comfort from the withdrawal of the threat of U.S. bombing raids following a deal under which he has agreed to give up his chemical weapons.
Shi'te Iran has already spent billions of dollars propping up Assad in what has turned into a sectarian proxy war with Sunni Arab states.
And while the presence of Iranian military personnel in Syria is not new, military experts believe Tehran has in recent months sent in more specialists to enable Assad to outlast his enemies at home and abroad."
Take that all in..
But in a way how strange is it all really?
Just last year President Obama was about to commit US forces into Syria to fight for the first time ever since 9/11 alongside al Qaeda, the ones responsible for the attacks
Of course every single person involved in 9/11 was Saudi Arabian born but shhh... That's our ally.
Well.. if written in 1979...