In 1077, the Holy Roman Emperor, Henry IV, asked the Pope, Gregory VII, for forgiveness during the Investiture Controversy, a conflict inspired, at least in part, by Gregorian Reform. While the Emperor was travelling to ask pardon, Gregory believed that he was going to arrest him, and hid in a castle at Canossa. Henry stood outside wearing only a hairshirt, barefoot in the winter snow, and asked forgiveness. Gregory denied him. Three days passed, and eventually the Pope was forced to forgive him.

de:Gang nach Canossaja:カノッサの屈辱