Three big incidents:
1. Titanic (or was the olympic) sinking of wealthy elite. Plus/Min 20 years later. World War 2.
2. 9/11/2001 World Trade Center attack. Plus/Min 20 years later war between Ukrain and Russia. Basically US/EU vs Russia.
My hypothesis is:
When the wealthy elite are mass-murdered (by evil jealous forces) 20 years later war breaks out. This is because the jealous evil forces are incompetent to run big economic things and they evil anyway.
As always to prove an hypothesis it must predict something.
Now my prediction was: something must has happened 20 years before World War 1 unknown to me.
So I look it up, and bingo, precisely on the date:
World War 1 started in 1914. Thus for my hypothesis to be correct/to be considered proven something must have happened 20 years earlier:
1894–1896: Sultan Abdul Hamid II ordered Ottoman forces to kill Armenians across the empire. Deaths: 100,000–300,000
(I also came across egypt invasion, not on list ?, lots of things happen in the world)
The moral of the story: Perhaps you should respect your elite, making nice/good trade agreements. A trade agreement is better than no trade agreement =D