About Carlos Hugo, Duke of Parma
Carlos Hugo, Duke of Parma and Piacenza was the head of the ducal House of Bourbon-Parma from 1977 until his death. Carlos Hugo was a Carlist claimant to the throne of Spain and sought to change the political direction of the Carlist movement through the Carlist Party, of which he was the official head during the fatal Montejurra incidents. His marriage to Princess Irene of the Netherlands in 1964 caused a constitutional crisis in the Netherlands. Carlism is a Spanish political movement founded in the 19th century to uphold the claim of Carlos Hugo's branch of the House of Bourbon to the Spanish throne.
Biography source: Wikipedia. The profile adds birthday-specific historical context from the Celebs Birthday Today editorial database.