the local settler population. (The island was split along the Camuy and Jacaguas rivers.) Since most of the settlers did not have the training to become governors, the system proved ineffective. The island's Spanish residents complained to the Crown. Starting in 1545 governors with legal training (gobernadores letrados) were appointed by either the crown or the Santo Domingo Audiencia. Filling the highest judicial office on the island, the governors heard cases in the first instance in their immediate districts, and in appeal from the regional alcaldes. The next court of appeal was the Audiencia in Santo Domingo. In addition to being the highest administrative office on the island, governors also derived power from their right to annually appoint two of the four regidores of the cabildos on the island. As with all other Spanish political officials, governors were subject to the juicio de residencia, an official review of their time in office. Since governors were the king's highest representative on the island, they had oversight over the Church because of the right of patronage (real patronato) that the monarchs of Spain had in the Americas. They controlled the construction and maintenance of church buildings, paid the salaries of the clergy, and ensured that only Papal bulls and encyclicals approved by the Council of the Indies were published on the island. Due to Spain's growing military conflicts with other European powers, both in Europe and in the New World, the Crown added the office of captain general to the governor in 1580. Following this, mostly military men, rather than lawyers, were appointed as governors-captains general. They were assisted by a legal adviser (asesor) in their judicial and administrative duties. Establishment Spain considered Puerto Rico as vital strategically as the gateway to the Caribbean, even as it was economically marginal. It was described as "the key to the Indies." Given the sea currents and wind patterns of the Atlantic, Puerto Rico was usually the first port of call for ships arriving from Europe. Despite this, or perhaps because of its negligible economic importance, the Spanish took a long time to build up the island's defenses. The first fortified building was the Ponce de León family home (today the Casa Blanca), which defensive features were added in the 1520s. In the next decade construction began on the first true fort, La Fortaleza, at the entrance of the bay. By 1539 construction began of