Spain began developing a New World empire when men such as Christopher Columbus started searching for a shorter route to the spices available in the Orient. Although they could not find a shorter passage, explorers soon discovered that the Americas offered other equally profitable resources—most notably vast quantities of gold and silver.

In 1493, Columbus became the first European to visit Puerto Rico, an island situated at the gateway to the Caribbean from Europe. The Spanish then ignored the island until 1508, when Juan Ponce de León established a small settlement there he called Caparra. Puerto Rico then became part of an empire that would last until the end of the 19th century. "New Spain," as the government called the territory it claimed in the Americas, at times extended from Florida down through South America, from the eastern end of the Caribbean across Central America to the Pacific Ocean. Spain soon discovered that its people and possessions needed protection from both the native population it tried to control and from other European nations who also wanted the region's wealth. To protect its empire, Spain developed a series of forts; among the most important were those in Puerto Rico.