The Siege of London
190 A.D.: English settlers babbling about "escaping religious persecution" are captured fleeing London, and sent back to the Republic to work as serfs on the road connecting York and Nottingham.
I can't let settlers past my lines, or the English will just found a new city somewhere off in the wilderness for me to waste time finding and capturing. By moving over the undefended unit with a military unit, they become a worker under my control.
205 A.D.: English scouts are found and executed in the forests outside Edinburgh.
To the North, the Siege of London begins.
Word arrives from across the sea of another new religion, Buddhism.
And then there were three. I've decided to nickname this one Sonyism.
220 A.D.: The second Swedish-German War begins.
This is good. I'm on better terms with Sweden than almost anyone at this point, and any time their "Declare War" roulette wheel lands on Germany or Russia, my enemies are weakened without me having to do much of anything.