In 1462, the confrontation between King Juan II of Aragon (1458-1479) and the institutions of Catalonia, which had been brewing since the beginning of his reign, broke out in a civil war that lasted for ten years and reached an international dimension. The Diputación del General of Catalonia, which controlled Barcelona and a large part of the principality, granted the crown successively to King Enrique IV of Castile (1462-1463), Constable Pedro of Portugal (1464-1466), son of the Infante Pedro, Duke of Coimbra, and Renato de Anjou, Count of Provence (1466-1472).
Of the three, only Pedro of Portugal personally led the government, while Enrique IV and Renato de Anjou delegated lieutenants. All of them, however, maintained the usual administrative system in the Crown of Aragon until then, organized around a Chancery that continued issuing the documentation of the king and his lieutenants, copied in the volumes of the different series of registers already established in the previous reigns.
On November 13, 1472, barely a month after the capitulation of Pedralbes that ended the civil war with the victory of King Juan II of Aragon, he enacted a decree with regard to the books that contained "the trials, donations, deliberations, edicts and decrees" (i.e., the Chancery registers) of his enemies who usurped the crown during the previous ten years. In keeping with the pragmatic and conciliatory spirit of the capitulation, he ordered them to be kept, alleging that they would serve as an example of the unjust rule of tyrants over the government of legitimate princes, and also that in the future something beneficial could be found in them, "since there is no book, no matter how bad, that won't at some point come in handy". The punishment of the memory of his enemies was limited to these records being kept separate from the rest of his Archive, blacking them out, and marking them with the "thita" (θ), "a fatal Greek letter" and symbol of death designating the condemned.
Thanks to this decree being carried out, today we can study the documents and registers of the claimants to the throne who were in the end defeated by Juan II. Following this precedent, the records of Louis XIII and Louis XIV of France and those of Archduke Charles of Austria, claimants to the crown in the period of the Reapers' War (1642-1652) and of the War of Succession (1705-1713) respectively were also preserved. All of them are preserved under the name of "Registers of Intruding Kings" and can be consulted in the Archive Reading room.