And so, as there were many financial interests concerned in protecting slavery, every effort to effectually abolish the trade was met by an outcry and by shrewd political opposition.
The slaves were better off in the United States than at home, Congress was assured; they had the blessings of Christianity; were freed from the endless wars and perils of the African jungle.

Moreover, they were needed to develop the South, while in the trade, the hardy and daring sailors were trained, who in time would make the American navy the great power of the deep.

Political chicanery in Congress reinforced the clamor from without, and though act after act for the destruction of the traffic was passed, none proved to be enforcible--in each was what the politicians of a later day called a "little joker," making it ineffective.

But in 1820 a law was passed declaring slave-trading piracy, and punishable with death.
So Congress had done its duty at last, but it was long years before the Executive rightly enforced the law.
It is needless to go into the details of the long series of Acts of Parliament and of Congress, treaties, conventions, and naval regulations, which gradually made the outlawry of the slaver on the ocean complete.

In the humane work England took the lead, sacrificing the flourishing Liverpool slave-trade with all its allied interests; sacrificing, too, the immediate prosperity of its West Indian colonies, whose plantations were tilled exclusively with slave labor, and even paying heavy cash indemnity to Spain to secure her acquiescence.