Princess Irene of the Netherlands

Although it was a constitutional tradition and not a law that forbade a Catholic to reign over the Netherlands, it was a practice predicated upon a history of the Protestant-dominated Dutch Parliament (States-General) born out of the 16th century war with Spain. Fears of Catholic domination had increased over the centuries through difficulties and wars over the policies of many neighboring Catholic European countries and the precedent created by the ascension of a member of the House of Orange to the throne of the Kingdom of England solely because he was Protestant. By the middle of the 20th century religious attitudes had begun to change, but only very slowly. While members of the Roman Catholic Church accounted for approximately 34% of the Dutch population, and Catholic political parties had been in coalition governments since 1918, the high fertility rate of the Catholics was a matter of some concern for all non-Catholics.

Amplifying the crisis over a Royal conversion to Catholicism and a marriage without approval of the Dutch States-General (which the Princess, then second-in-line to the throne, knew she would never get), were the still very fresh memories of General Franco's support for Nazi Germany. For the second in line to the throne not merely to convert to Roman Catholicism but associate with an alleged leader of Franco's party, caused shock and consternation in the Netherlands.

Links:

• The Peerage
• Geneall
• Johann the Younger #3185
• Wikipedia

https://religion.fandom.com/wiki/Princess_Irene_of_the_Netherlands