An emperor in penitent's clothes before the pope

The Penance of Canossa is an episode of submission of Emperor Henry IV to Pope Gregory VII in January 1077. Excommunicated by the papacy for having contested its authority, the emperor had to beg for his forgiveness in penitent's clothes to avoid deposition by the German princes. This event marked a reversal of powers since, thirty-one years earlier, the emperor still commanded the popes.