This office was transferred to America during the conquest and was usually granted along with the hereditary governorship to the adelantado in the patent issued by the Crown.
This established a precedent that was recognized by the New Laws of 1542, but ultimately the crown eliminated all hereditary governorships in its overseas possessions.
With the establishment of appointed governors, who served only for a few years, captaincies were created in the areas where the crown deemed them necessary.
However, in practice this was a person who held two distinct offices: one military, which granted him command of the regional forces (the "captaincy general" proper), and another civilian, which included the presidency of the audiencia, if there was one in the provincial capital, (the governorship).
Although under the nominal jurisdiction of their viceroys, governors-captains general were virtually independent, because the law granted them special military functions and given the considerable distance of their districts from the viceregal capital, they were authorized to deal directly with the King and the Council of the Indies, in Madrid.