Another What-If

Most of the time you'll find what-ifs for an alternate history based on a battle. Why? In part, that's because there's documentation for the battle. In part, the consequences can be seen. This isn't necessarily the case for non-battle causes.

Let's look at ones I've used:

1. Jutland - it's decisive for the British;
2. Gallipoli - an enterprising officer doesn't stop on Suvla Beach, but moves inland to capture the critical heights, cutting the Gallipoli Peninsula in two;
3. Falling Waters - Meade attacks right away;
4. Minden - Sackville charges;
5. Rome, 370 AD - modern saboteurs blow up the Senate and Emperor. Okay, not a what-if, but it was how I could generate a new timeline.

The only one I've used in a story that didn't feature a battle was Oswald Mosley becoming British Prime Minister in 1936 (an outgrowth of Edward VIII not abdicating). But it could have happened, and there was a lot of documentation about it.

Picking a Cause Event (CE) that is not based on a battle is harder. The classic one was H. Beam Piper's Aryan Transpacific, where the local shaman took it in his head to go east with the Aryan migration, not west. An off-shoot ended up populating North America. See Lord Kalvan of Otherwhen by Piper, and Tangent by Gina Marie Wylie (you'll find it on the web). People pick battles for their splits because it's easier, the most popular being Gettysburg and Waterloo (and only a few picking Antietam). Let's look at a few others.

1. Francis II does not die early from an abcess in his ear; this lead to an extended regency and religious civil wars in France.
2. Nero blames some other small group for problems in Rome, not the Christians. Not sure what this will do, have to dialogue it out sometime.
3. In 1914 the German Foreign Minister decides not to give Austria-Hungary a blank check on what to do about Serbia. WW1 would probably have still broken out, just not in July/August of 1914.
4. Julian Apostate (Emperor of Rome) puts on his armor before rushing to lead his troops in a counterattack (when he was subsequently assassinated by a Christian zealot). Christianity might have suffered from a major survival problem with somebody willing to massacre freely.

These are nowhere near exclusive, just ones I could think of off the top of my head. These splits don't have to be the primary cause of a time split in a story, they can just be something that leads to an important plot twist in a story. Most (but not all) revolve around whether somebody would survive. Most admit of some deep currents in the affairs of mankind, but more as a cultural baggage, not of major events. I realize that this suggests mankind has a hand in its own fate, but that's a discussion for some other time.