Ferdinand and Isabella ruled Aragon and Castile jointly from 1474 to 1504, a thirty-year period during which the modern country of Spain was born, ships they commissioned discovered and explored the New World, and the Spanish Empire was formed in the Western Hemisphere. Spain achieved its peak during the reigns of their next two successors (Charles and Phillip), who largely preserved and built upon the policies and institutions they founded. Each of them was already a monarch when they married, and during their marriage, they shared power over both kingdoms. In other words, it was not an instance of one person wearing the crown and the other merely being the spouse/consort. (One could argue over whether their powers were equal, but that's an argument for a different question. The fact is, they both had royal power.)

I want to fairly and accurately state Ferdinand and Isabella's importance relative to other royal couples. My question is, would it be correct to state that they were the most important royal couple in world history? In European history? In medieval European history? Or if "important" doesn't work, what about another adjective that does (successful, famous, influential, etc.)?

Just to stress the point, I'm uninterested in comparisons with royal couples where only one member was actually a monarch (regardless of how much behind-the-scenes influence his/her spouse is believe to have had).

  • 2
    en.wikipedia.org/wiki/Eleanor_of_Aquitaine Duchess, not Queen, but married to 2 different Kings; Important on the convoluted history of french fiefs owned/claimed by England (lead to the 100y war).
    – Luiz
    Aug 11, 2021 at 0:29
  • britannica.com/biography/Isabella-II-queen-of-Jerusalem when very young, married Emperor Frederick II, who claimed her authority to himself (besides consummating the marriage ahead of time). Died giving birth. Sad short life. Ferdinand/Isabella set a high bar to compare.
    – Luiz
    Aug 11, 2021 at 0:35
  • Can you revise to avoid bad subjective? To make an authoritative answer possible?
    – MCW
    Aug 11, 2021 at 0:39
  • The importance of a royal couple can be argued with facts, examples, and logic. Knowledgeable people ought to be able to reach a consensus on whether there are other good contenders for the distinction, who they are, and why. Or perhaps there are one or more royal couples who blow them out of the water and I was an idiot for not remembering. So yes, It is a subjective question, but how is it "bad"? It's not like asking which is the best Beatles song or the most delicious flavor of pie.
    – davo
    Aug 11, 2021 at 14:15
  • Your last requirement sends this into No True Scotsman twrritory.
    – Spencer
    Aug 11, 2021 at 16:08

2 Answers 2



This one is comparable to Ferdinand and Isabella. The Queen of Poland married the King of Lithuania, which sealed the conversion of the king and of Lithuania itself to Catholicism from paganism (thus ending the pagan raids on Christians and the Baltic crusades), and the formation of the PLC, one of the largest countries in Europe for a long time afterwards.

Ferdinand/Isabella set a high bar to compare others, but just to cite other cases, probably farther from the mark:


Duchess, not Queen, but her duchy was important, and she married to 2 different Kings (France and England); Important on the convoluted history of french fiefs owned/claimed by England (which lead to the Hundred Years war). She had authority at least during parts of her complex life, she even may have revolted against her husband with her sons.


when very young, married Emperor Frederick II, who claimed her authority to himself (besides consummating the marriage ahead of time and maybe also raping her cousin-companion who traveled with her). Died giving birth, after a sad short life. Her importance was involving her husband with the crusades. And, this case is Queen+Emperor, not Queen+King.


The rule of William III and Mary II of England started the modern period in the history of this country. William could claim the English throne because we was married to Mary, the daughter of James II. And they came to power as the result og the so-called Glorious revolution. England became a true constitutional monarchy, as it is now, as a result of this revolution.

  • 4
    Not comparable. William and Mary were offered the throne jointly as a sop to succession /primogeniture laws - Mary was James' II eldest daughter, William merely a nephew. But all executive power was vested in William: firstly, because William would not have accepted any other terms, and, secondly, Mary, as a dutiful Protestant wife, was genuinely shocked at the idea of outranking her husband, an arrangement she thought contrary to God's law of the man being the 'head' of the woman. They both reigned: William ruled.
    – TheHonRose
    Aug 11, 2021 at 16:17
  • Before they were offered throne, they had to invade England with huge force:-)
    – Alex
    Aug 11, 2021 at 16:19
  • 1
    Only after William had been invited by members of the elite! And William - supported by his wife, whose claim to the throne was better - made it clear he would not be a mere consort to Queen Mary.
    – TheHonRose
    Aug 12, 2021 at 5:09
  • PS William invaded. Mary didn't.
    – TheHonRose
    Aug 12, 2021 at 7:50

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.