On January 8, 1297, the founder of the Grimaldi dynasty of Monaco, François Grimaldi (1201? – 1309), disguised himself (and his supporters) as monks and captured the fortress protecting the Rock of Monaco. 
 

François Grimaldi –  Malizia 1201 – 1309
Issued by Monaco for their EUROPA 2022: Stories and Myths stamps
Artist/designer: Artist: Alain Giampaoli

 Civil strife in Genoa between the Guelph and Ghibelline families resulted in many taking refuge in Monaco, among them the Guelph family. Son of Otto Canella, Consul of Genoa in 1133, Grimaldo began the House of Grimaldi, the future ruling family of Monaco.

In 1297, François Grimaldi (“Malizia”, translated from Italian as “The Cunning”) disguised as a Franciscan monk alongside his cousin Rainier I and his men captured the fortress atop the Rock of Monaco. History of Monaco (monacodc.org)