The evil principle of Pythagoras. Accordingly the second day of the second month of the year was sacred to Pluto, and was esteemed unlucky.
It does not seem much more lucky abroad: Charles II. of France, after a most unhappy reign, died of poison; Charles II. of Navarre was called The Bad; Charles II. of Spain ended his dynasty, and left his kingdom a wreck; Charles II. of Anjou (le Boiteux) passed almost the whole of his life in captivity; Charles II. of Savoy reigned only nine months, and died at the age of eight.
Francois II. of France was peculiarly unhappy, and after reigning less than two years, sickened and died; Nepoleon II. never reigned at all, and Nepoleon III., really the second emperor, was á most disastrous prince;
Franz II. of Germany lost all his Rhine possessions, and in 1806 had to renounce his title of emperor. Friedrich II., Emperor of Germany, was first anathematised, then excommunicated, then dethroned, and lastly poisoned.
Jean II. of France, being conquered at Poitiers, was brought captive to England by the Black Prince; Juan II. of Aragon had to contend for his crown with his own son Carlos.
It was Felipe II. of Spain who sent against England the “Invincible Armada”; it was Francesco II. of the Two Sicilies who was driven from his throne by Garibaldi; it was Romulus II. in whom terminated the empire of the West; Peter II. of Russia died at the age of fifteen, and he was a disgrace to the name of Menschikoff; Pietro II. de Medicis was forced to abdicate, and died of shipwreck; James II. of Scotland was shot by a cannon at the siege of Roxburgh; James II. of Majorca, after losing his dominions, was murdered. Alexander II. of Scotland had his kingdom laid under an interdict; Alexander II., the Pope, had to contend against Honorius II., the anti-pope; Alexis II., Emperor of the East, was placed under the ward of his father and mother, who so disgusted the nation by their cruelty that the boy was first dethroned and then strangled; Andronicus II., Emperor of Greece, was dethroned; Henri II. of France made the disastrous peace called La Paix Malheureuse, and was killed by Montgomery in a tournament; etc. etc (See Jane and John.)
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894
More on Two from Infoplease: