From the beginning of the country, the colonial administration relied heavily on the industry of enslaved Africans and creole blacks for public works and defenses, primarily in coastal ports and cities, where the tiny colonial population had hunkered down. With no significant industries or large-scale agricultural production as yet, enslaved and free communities lodged around the few littoral settlements, particularly around San Juan, also forming lasting Afro-creole communities. Meanwhile, in the island's interior, there developed a mixed and independent peasantry that relied on a subsistence economy. This mostly unsupervised population supplied villages and settlements with foodstuffs and, in relative isolation, set the pattern for what later would be known as the Puerto Rican Jíbaro culture. By the end of the 16th century, the Spanish Empire was diminishing and, in the face of increasing raids from European competitors, the colonial administration throughout the Americas fell into a "bunker mentality". Imperial strategists and urban planners redesigned port settlements into military posts with the objective of protecting Spanish territorial claims and ensuring the safe passing of the king's silver-laden Atlantic Fleet to the Iberian Peninsula. San Juan served as an important port-of-call for ships driven across the Atlantic by its powerful trade winds. West Indies convoys linked Spain to the island, sailing between Cádiz and the Spanish West Indies. The colony's seat of government was on the forested Islet of San Juan and for a time became one of the most heavily fortified settlements in the Spanish Caribbean earning the name of the "Walled City". The islet is still dotted with the various forts and walls, such as La Fortaleza, Castillo San Felipe del Morro, and Castillo San Cristóbal, designed to protect the population and the strategic Port of San Juan from the raids of the Spanish European competitors.