Construction on the Castillo San Felipe del Morro (El Morro) began in 1539 by the Spanish to offer protection to the city of San Juan, Puerto Rico. Originally just a small fort, the fortress was expanded in 1587 to look as it does today. The British attacked the fort in 1595, but the Spanish retained possession. Another attack by the British in 1598 was successful, but the British abandoned the fort after an outbreak of dysentery. The Dutch tried attacking the fortress from land, but the fort held strong. During the Spanish-American War the United States bombarded the fort and city several times and in 1898 the Spanish ceded the island to the United States (along with Cuba, Guam and the Phillipines). The United States turned the fort and several San Juan buildings into Fort Brooke. During World War I the fort actually fired shots. The United States added a lighthouse and bunker during World War II so the Army could use the base to hunt for German submarines. The fort was retired in 1961 and became a national park.