Originally Posted by CyrilVladisla
Was it necessary that King Constantine I of Greece had to abdicate in 1917?
Seeing the tumbling thrones in Austria-Hungary, Russia, Germany, etc. by hindsight the abdication of Constantine I was a wise move. The same can be said about the abdication of Grand-Duchess Marie Adelheid of Luxembourg in 1919, which was just on time to save the monarchy.
An abdication (apart from the ones because the monarch him- or herself wants to retreat, like Charles V in 1555, or like Beatrix in 2013) always has a reason. Usually it is a result of a conclusion sinking in that a monarch does not have sufficient support anymore. This was the case with Constantine I and Marie Adelheid, amongst others.