Diego Duque de Estrada (August 15, 1589, in Toledo, Spain – 1647) was a Spanish memoir writer, soldier and adventurer.
One night, he found an intruder in the house, a gentleman with whom he was acquainted, and in a fit of jealousy, killed both him and the young lady.
The prevailing code of honor was considered a sufficient justification for Estrada's violence, but the law looked upon the act as a vulgar assassination, and he had to flee.
After the fall of his patron, Duque de Estrada resumed his vagabond life and served under Bethlen Gábor in Transylvania and the Thirty Years' War.
Still, they are amazingly vivid and contain a wonderful picture of the moral and intellectual state of a large part of Spanish society at the time.