I think I found out where to look for military records of individuals that served in the americas. Such as Nueva Espana (Mexico):

https://www.familysearch.org/wiki/en/Spain_Military_Records

I think I found out where to look for military records of individuals that served in the americas. Such as Nueva Espana (Mexico):

https://www.familysearch.org/wiki/en/Spain_Military_Records

The records of those that served in the Americas are found in the General Archive of Simancas. These records include the following places:

Buenos Aires
Cuba
Chile
Philippines
Guatemala
Nueva España (originally Mexico and Central America except Panama)
Viceroyalty of Peru (originally included most of Spanish South America)
Indias (Florida, Puerto Rico y Venezuela)

Archive of Simancas?
http://www.mecd.gob.es/redirigeme/