>>17799480 (OP)Do you know about Charles II, the last Hapsburg monarch of Spain? Due to extensive inbreeding he was born with a number of severe birth defects including developmental delay and impotency. Today he would be considered borderline mentally retarded, yet despite this he was made king and given (at least on paper) absolute power, and a beautiful wife. Presumably because of his birth defects he was never able to father any children and he died at 35.
Without any family the question of who would succeed him had long been troubling to the nations of europe, and on his deathbed Charles declared that his grandnephew Philip V Duke of Anjou, should inherit the throne. The problem was that the duke was the grandson of Louis XIV and this meant that Spain and France would from then on be natural allies, and worse he could potentially become king of both Spain (which held a great deal of european territory outside of iberia) AND France. The prospect of this superstate was a truly terrifying one to the English, Austrians, Dutch, and most of the HRE. So on Charles' death they refused to recognize Phillip and shortly afterwards declared war in the hopes of partitioning Spain's empire and removing him from the throne.
This was the start of the "war of spanish succession" which raged for 12 years and claimed over half a million lives. It was also the beginning of the end for the Spanish Empire.
And to think, there are people who still think that Monarchy is a good form of government after one placed a literal impotent retard on the throne, whose death triggered a massive and ruinous war.