For example, Boris III of Bulgaria and his son Simeon II were given their regnal numbers because the medieval rulers of the First and Second Bulgarian Empire were counted as well, although the recent dynasty dates only back to 1878 and is only distantly related to the monarchs of previous Bulgarian states.
Also, in the case of Emperor Menelik II of Ethiopia, he chose his regnal number with reference to a mythical ancestor and first sovereign of his country (a supposed son of biblical King Solomon) to underline his legitimacy into the so-called Solomonic dynasty.
In any case, it is usual to count only the monarchs or heads of the family, and to number them sequentially up to the end of the dynasty.
Similarly for the House of Reuss, where all men were numbered Heinrichs and some were reigning Princes of Reuss-Gera or Reuss-Greiz.
Ordinals are also retrospectively applied to earlier monarchs in most works of reference, at least as far as they are not easy to distinguish from each other by any other systematical means.
As a rule of thumb, medieval European monarchs did not use ordinals at their own time, and those who used were rarities and even their use was sporadic.
Popes were apparently the first to assume official ordinals for their reigns, although this occurred only in the last centuries of the Middle Ages.
The British tradition of consistently and prevalently numbering monarchs dates back to Henry VIII and Mary I; however, sporadic use occurred at least as early as the reign of Edward III.
After the realms were united with the Acts of Union 1707, separate numbers were not needed for the next five monarchs: Anne and the four Georges.
[citation needed] (George Croly pointed out in 1830 the new king was William I, II, III, and IV: of Hanover, Ireland, Scotland, and England respectively.
A court case, MacCormick v Lord Advocate, contesting the style "Elizabeth II" within Scotland, was decided in 1953 on the grounds that the numbering of monarchs was part of the royal prerogative, and that the plaintiffs had no title to sue the Crown.
To rationalise this usage, it was suggested by Winston Churchill, the Prime Minister of the day, that in future, the higher of the two numerals from the English and Scottish sequences would always be used.
[9] This had been the case de facto since the Acts of Union 1707; nine of the thirteen monarchs since the Act had names either never previously used in England or Scotland (Anne, six Georges, and Victoria) or used in both only after the 1603 Union of Crowns (three Charleses), which sidestepped the issue, while the English numbers for the remaining four monarchs' names have consistently been both higher and the ones used (William, two Edwards, and Elizabeth).
This is a more recent invention and appears to have been done for the first time when Francis I of France issued testoons (silver coins) bearing the legend FRANCISCVS I DE.
This currently is the regular practice in Spain and Monaco (at least for Prince Albert I, as Princess Louise Hippolyte, who reigned 150 years earlier, does not appear to have used an ordinal).
It was also applied in Brazil, Greece, Italy, Mexico, Montenegro, Portugal (where Kings Joseph, Louis and Charles are usually referred to as "Joseph I", "Louis I" and "Charles I" although there has not yet been any Joseph II, Louis II or Charles II, but Kings Denis, Edward, Sebastian and Henry are usually referred without the ordinal).
In Ethiopia, Emperor Haile Selassie used the "I" ordinal (Ge'ez: ቀዳማዊ, qädamawi) although previous Ethiopian monarchs had not used it, and they are not referred as "the first" unless there were successors of the same name.
The current Pope Francis has declined the use of an ordinal, but on the other hand, his Orthodox counterpart, Patriarch Bartholomew I of Constantinople, uses one, as does Aram I, the catholicos of the Armenian Apostolic Church.
Three of those names were previously the names of Austrian Archdukes (the Archduchy of Austria was a state within the Holy Roman and the Austrian Empires), which makes three of these emperors Francis II, Ferdinand V, and Charles IV in their capacity as Archdukes.
The use of "The First" ordinal is also common to self-proclaimed ephemeral "kings" or "emperors", such as Napoleon I in France; Dessalines, Christophe and Soulouque in Haiti; Iturbide in Mexico; Zog in Albania; Bokassa in the Central African Empire; Skossyreff in Andorra; Theodore in Corsica; and "Emperor" Norton in San Francisco.
Although the child died in prison a few years later and never reigned, his uncle, who came to the French throne in the Bourbon Restoration, took the name Louis XVIII in acknowledgement of his dynasty's rights.
They numbered themselves separately for Scotland and England because they did not recognize the Acts of Union, which joined the two kingdoms into one in 1707, as valid.
This custom is currently not followed by any other ethnic groups other than the French and British (Jacobites), being unique to them, monarchists from other nations do not usually use royal numbers for the pretenders they support.