Blast from the past. When Irish Vets from the US Civil War invaded Canada...

Canadian militiamen stand over the body of a recently killed Irish soldier who was one of around 1000 Irish veterans from the American Civil war who invaded Canada in 1866 to attack British interests. Fort Erie, June 2nd 1866

History is a glorious thing.  The second you think you have even a BASIC grasp of things an unknown event is presented that shocks and amazes.

I never knew this happened.

Just plain wow.