The garrisons (not very large) were normally to protect the Franciscan missions, which extended all the way up from St Augustine, FL through North Carolina.
The Franciscans actually worked hard to keep the Spanish soldiers away from the Indians, but the big problem came when the missionaries prohibited polygamy (women were sort of traded around by the Indians, even though some of the tribes or language groups transmitted power through the female line).
The interesting thing is that the only places where the different Indian groups survived were the Spanish areas. The British either killed them or enlisted them to fight against the Spanish.
The Spanish converted and, very often, married them. When the British destroyed the Florida Franciscan mission chain in the early 18th century, they killed many Indians and friars...and sent 11,000 Indians off as slaves to the British sugar plantations in the Caribbean. That virtually wiped out the Indian population of many parts of the Southeast.
Do you have a book on this topic? I think this would be very interesting reading.
There is some pretty strange history there, you have it sounding like the colonists were blood thirsty genocidal murderers creating the horrors called the Untied States and Canada, and the Spaniards were building sweet little paradises where they went, like with the Aztecs and while creating the nightmares we call Mexico and other Spanish areas.
What a peculiar history. What is your source, the Catholic Encyclopedia?
And, what about the Franciscans themselves as far as indian women? One of my legendary ancestors is Opechancanough, half brother of Powhatan, he was fathered by a Spanish missionary.