The Father-in-law of Europe is a sobriquet which has been used to refer to two European monarchs of the late 19th and early 20th century: Christian IX of Denmark and Nicholas I of Montenegro, both on account of their children's marriages to foreign princes and princesses. The fact that each was a monarch of moderate or modest power (and thus a marriage would not threaten the delicate balance of power) allowed them to marry some of their many children to heirs of greater fortunes across the continent.