Once upon a time, there was a Holy Roman Emperor named Henry IV. He wasn't a big fan of the Catholic Church having control over his business. In particular, he wanted to be able to assign his loyal subordinates as bishops within the Empire. Pope Gregory VII felt differently about the matter.
This all more came to a head when the two of them assigned separate candidates for the same position. Fuming, the Pope decided to push the big red button. The one marked "excommunicate." He notified Henry that he had exactly one year to prove that he's stopped being a dick about this whole investiture thing.
|All while giving the "Oh no you didn't" finger wag|
So Henry had to do something. In the Winter of 1077, he got an entourage together in Speyer and headed South, away from Germany and across the Alps toward Canossa. Legend has it that he made the journey barefoot, wearing a cilice, braving frigid temperatures, snow, and ice the whole way. When he arrived, he found that the Pope ordered the gates closed. So he knelt in the snow.
|And after the whole "uphill both ways" journey, too.|
|I mean, how could you not?|
Even today, people of many countries refer to a humiliating apology as their "Walk to Canossa." Just goes to show that a little hiking can do a lot for history and colloquial language.