 Prior to the eighteenth century, Spain's territories in the Americas were mainly defended through a series of Spanish military units being based in strategic coastal port cities and important economic centers.But as European rivals began to challenge the Spanish crown and their dominance in the new world, the Bourbon dynasty initiated a series of reforms, allowing people from their colonies to serve in the regular armies, as well as permitting local militias in their territories.While these groups began to integrate themselves into the official Spanish colonial militaries, free-colored militias have been reluctantly used since the-mid sixteenth century.