Original sentence: Regarded by his victims as a pirate, Bouchard was technically a corsair from the then very young free state of the "United Provinces of Rio de la Plata River," (direct ancestor of the present Argentine Republic)
Edited sentence: Most often regarded as a pirate, Bouchard was technically a corsair from the then very young free state of the "United Provinces of Rio de la Plata River," (direct ancestor of the present Argentine Republic)