The main purpose of the Spanish Armada's 1588 expedition was to invade England and overthrow Queen Elizabeth I to restore Catholicism as the dominant religion. King Philip II of Spain sought to eliminate the Protestant threat posed by England and its support for the Dutch Revolt against Spanish rule. The Armada was meant to escort a large invasion force to capture English ports, but it ultimately failed due to strategic miscalculations, poor weather, and the resilience of the English navy. This defeat marked a significant decline in Spanish maritime power and the rise of England as a leading naval force.