Philip III of Spain was the king of Spain from 1598 until his death in 1621. He was born on April 14, 1578, and was the son of Philip II of Spain and Anna of Austria. His reign is often characterized by a focus on peace and diplomacy, particularly through the signing of the Treaty of London in 1604, which ended hostilities with England. Philip III's rule saw the decline of Spanish power, partly due to economic difficulties and military challenges. He relied heavily on his favorite, the Duke of Lerma, who influenced many of his decisions. Despite his efforts to maintain stability, his reign is often viewed as a period of stagnation for the Spanish Empire.