Contrary to much of the current slavery apologist propaganda, the slave trade was furiously controversial in both England and Spain right at the beginning, as was Spanish treatment of native Americans. Clergymen and philosophers railed against it, and many sea captains and common sailors refused to have anything to do with it. The profits were phenomenol however and successive governments found ways to allow it, mostly on the grounds that if we don’t reap those profits, someone else will. By the 18th century the opposition had become muted, almost resigned to it, only to be revived during the Enlightenment. This revival of anti-slavery agitation was ultimately successful but only after an epic political, moral and military struggle.