Margaret of Austria, Queen of Spain in the context of "Philip III of Spain"

Philip III (Spanish: Felipe III, Portuguese: Filipe II; 14 April 1578 – 31 March 1621) was King of Spain and Portugal (as Philip II) during the period known as the Iberian Union, reigning from 1598 until his death in 1621. He was also King of Naples and Sicily, Duke of Milan, and Lord of the Seventeen Provinces. A member of the House of Habsburg, he was born in Madrid to King Philip II of Spain and his fourth wife, Anna of Austria. The family was heavily inbred; Philip II and Anna were uncle and niece, as well as cousins.

One year after inheriting the throne, he married his Habsburg cousin Margaret of Austria, the sister of Ferdinand II, Holy Roman Emperor. Philip quickly delegated most of his power and duties to his chief minister, the Duke of Lerma, whose influence shaped much of his reign. In the outskirts of his territories, military power was upheld by successful but capricious proconsuls, such as Ambrogio Spinola and the Duke of Osuna. Though Philip is associated with a period of relative peace in Western Europe, called the Pax Hispanica by some historians, his lack of focus contributed to the Spanish Empire's gradual decline.