Fig.: to humble oneself, doing an act of penance or submission

The economic situation got so desperate that the workers on strike went to Canossa and accepted something they thought they'd never settle for

La situazione economica si era fatta talmente disperata che i lavoratori in sciopero sono andati a Canossa e sono scesi a patti che altrimenti non avrebbero mai accettato

In January of 1077, Holy Roman Emperor Henry IV went, as a simple penitent, to Canossa castle to ask Pope Gregory VII, who was living there as a guest of Matilda of Tuscany, to pardon him and revoke his excommunication. Thanks to the intercession of the noble woman, the emperor was absolved by the Pope but only after three days of waiting, spent doing penance on his knees outside the castle gate in a bitterly cold blizzard