Canossa, in the duchy of Modena, is where (in the winter of 1076-7) Kaiser Heinrich IV. went to humble himself before Pope Gregory VII. (Hildebrand).
When, in November, 1887, the Czar went to Berlin to visit the Emperor of Germany, the Standard asked in a leader, “Has the Czar gone to Canossa?”
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894