Don Carlos (July 8 1545-July 24 1568), prince of Asturias, was the son of Philip II of Spain, by his first wife Maria, daughter of John III of Portugal, and was born at Valladolid. His mother died a few days after his birth, and the prince, who was very delicate, grew up proud, wilful and indolent, and soon began to show signs of insanity. In 1559 he was betrothed to Elizabeth, daughter of Henry II of France, a lady who a few months later became the third wife of his father; in 1560 he was recognized as the heir to the throne of Castile, and three years later to that of Aragon. Other brides were then suggested for the prince; Mary Queen of Scots, Margaret, another daughter of Henry II., and Anne, a daughter of Maximilian II, Holy Roman Emperor; but meanwhile his mental derangement had become much more acute, and his condition could no longer be kept secret.

In 1562 he met with an accident which was followed by a serious illness, and after his recovery he showed more obvious signs of insanity, while his conduct both in public and in private was extremely vicious and disorderly. He took a marked dislike to the Duke of Alva, possibly because he wished to proceed to the Netherlands instead of the duke, and he exhibited a morbid antipathy towards his father, whose murder he even contemplated. At length in January 1568, when he had made preparations for flight from Spain, he was placed in confinement by order of Philip, and in the same year he died. This event is still enveloped in some mystery.

Edited from Enyclopedia Britannica 1911

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