Janissaries were soldiers in the Ottoman Empire who had once been Christians, prior to their enslavement and forced service in the Ottoman army. Janissaries were an important component of the Ottoman armed forces and a significant component of Ottoman society.

In the fifteenth century, Spain was not a unified country and was instead divided into a few different kingdoms. With the marriage of Ferdinand of Aragon and Isabella of Castile, the unification of Spain was effectively complete. Their marriage marked the emergence of Spain as a colonial and global power.