On 25 January 1077, Henry IV ⓘ performed public penance before Gregory VII ⓘ at the castle of Canossa in northern Italy.

After the Synod of Worms (1076) and Gregory’s subsequent excommunication of the emperor, Henry faced rebellion among the German princes, who threatened to elect a new king unless the ban was lifted. Seeking absolution, Henry crossed the Alps in winter and travelled to Canossa, where the pope was staying under the protection of Matilda of Tuscany.

According to contemporary accounts, Henry waited outside the castle as a penitent before Gregory finally granted him absolution and lifted the excommunication. The episode became one of the most famous moments of the Investiture Controversy ⓘ, symbolizing the dramatic struggle between imperial and papal authority.