To be more specific: were there cases where citizens of the colonizing/imperialist power (be they intellectuals, idealists, or whatnot) played an active part in organized resistance? Not in our day and age, but in the earlier days of the Age of Sail/Age of Exploration periods.

As far as I know there were popes and great thinkers who had strong opinions on the matter, but I was wondering if there were records of more "direct" efforts. My guess is that it seems unlikely, considering the then prevailing world views, but I wouldn't mind being proven wrong.