Portugal however was one of the largest slave trading nations was Britains ally, so in 1810 under diplomatic pressure, a convention was signed allowing British ships to police Portuguese shipping meaning it could only trade in slaves from its own African possessions.
Portugal however was one of the largest slave trading nations and Britain's ally. So in 1810 under diplomatic pressure, a convention was signed allowing British ships to police Portuguese shipping meaning it could only trade in slaves from its own African possessions.