From the 16th to the 19th centuries, there was considerable Irish immigration to Puerto Rico for a number of reasons. During the 16th century, many Irishmen, who were known as "Wild Geese", escaped from forced service in the English Army and joined the Spanish Army. They did so either in Europe or when they could "jump ship" off the coast of Puerto Rico (whenever English ships came to trade or when the English Navy was engaged in attacks against the Spanish colonial forces on the island), at which time they joined the Spanish colonial army, mainly in San Juan.