In order to protect Spain’s interests in Guam and its Pacific trade routes, several fortifications were constructed to defend the island. Beginning with the first stockade in Hagåtña in 1671 and ending with the semi-reductos (half-enclosed parapets) in 1835, the Spanish administration built fourteen fortifications of various types and dimensions on Guam. Most of these defensive structures were open batteries designed for cannons to fire through embrasures. Six fortifications were constructed in the village of Hagåtña. Four fortifications were built to protect Umatac Bay. Three fortifications were built to defend Apra Harbor and one unnamed battery was assembled in Merizo to protect the anchorage outside the village.