So i am obsessed with looking back at human history and finding that "1 day(s)" that changed everything we come think of reality of today. ...
I always thought the battle of Hastings was a "Domino effect" on Europe and did my Highschool AP history presentation on how this one battle changed everything for "Medieval Europe" which would eventually lead to world war 1 which.. tail spun everything else as we know now.
Thennnn.... I'm sitting up clipping my 40k minis and watch a show "Barbarians" and how a band of German Barbarians defeat 3 Legions of Rome and cause the Romans to retreat out of Germany and most of northern europe forever more. ... then i see the "Roman Domino's" start falling. Gengis Khan then invades Rome a little while later which leads to more Barbarian uprisings later ... granted... Battle of Hastings was monumental for the way English/French relations came about but could the Battle in Teutoburg Forest be the linch pin for 2 millennia worth of history changing forever?
Germany and most of northern europe forever more. ... then i see the "Roman Domino's" start falling. Gengis Khan then invades Rome a little while later which leads to more Barbarian uprisings later
You may be thinking of Attila, leader of the Huns. The Mongol invasion led by Genghis Khan didn't reach Europe until the 13th Century and didn't really get further West than the Caucasus. The Hunnic invasions led by Attila occurred in the 5th Century, over 400 years after the Battle of Teutoburg Forest, at a time when the Roman Empire was already arguably in inorexible decline. Indeed, by the time that Attila began his campaigns against the Eastern Roman Empire in the 430s, more than 2 decades had passed since Alaric's Visogothic army had sacked Rome, and over 4 decades had passed since the first Roman garrisons started leaving Britannia.
At this point, I'd highly recommend this answer by /u/Tiako about the Crisis of the Third Century, which had a much more significant effect on the subsequent course of Roman, and indeed wider Eurasian history than the curtailing of Roman expansion into Germania in the early 1st Century.
I am highly curious as to seeing the logical progression from the Battle of Hastings to the Great War.