spains gradual decline By ryan.graves21 180 The Iberian Union of the crowns of Aragon, Castile and Portugal was established. Period: Jan 1, 1580 to Jan 1, 1898 spains gradual decline 1588 The Spanish Armada was defeated in the English Channel. 1598 Philip III of Spain was crowned. 1605 The Treaty of London (1604) was signed. 1618 The Expulsion of the Moriscos began. 1648 The Treaty of Westphalia was signed. 1659 The Peace of the Pyrenees was signed. 1665 Philip IV died.[2] 1675 Charles II of Spain was crowned.