What is "captain-major"

Captain-major is the English rendering of the Portuguese Capitão-mor, or the Capitães dos Donatários (Captains of the Donataries), the colonial officials, placed in charge of a Captaincy , deemed not (yet) important enough to have its own colonial Governor.

The term also applied as the rank title of the field officer that was in charge of a captaincy (group of companies) of the Ordenanças. The Ordenanças being the Portuguese territorial militia that existed from the 16th to the 19th centuries.