[JPJones]

“This sounds like a crock to me — obviously the same disadvantage a righty might experience confronted by a lefty applies reflexively, a lefty would have the analogous disadvantage confronted by a righty. “

No. Lefties (and righties) are used to fighting other righties.

A rhighty fighting a righty is the norm.

A rhighty fighting a lefty would be unusual only for the righty.

A lefty fighting a lefty would be very rare.

[SunkenCiv]

A lefty fighting a righty is no more common than a righty fighting a lefty, which is what I said up there.

[Verginius Rufus]

I was told once that in the Middle Ages, if two knights encountered each other on a path, each would go to his left (so that both had their right arms closest to the other, in case the other one was hostile and there would be swords drawn). The same rule applied to carts or wagons passing other carts or wagons, and that is how it is still done in England.

Then, during the French Revolution, they wanted to change as many things as possible (for the sake of change), and switched to riding or driving on the right. That spread to other countries but England rejected any innovations coming from the French Revolution (although they did eventually go to the metric system).

I'm not sure if that is correct or just an urban legend.