Toward the end of the sixteenth century this odious traffic was generally admitted, and it was not repugnant to the still barbarous manners.  All the States protected it so as to colonize more rapidly and more surely the isles of the New World.  In fact, the slaves of black origin could resist the climate, where the badly acclimated whites, still unfit to support the heat of intertropical climates, would have perished by thousands.  The transport of negroes to the American colonies was then carried on regularly by special vessels, and this branch of transatlantic commerce led to the creation of important stations on different points of the African coast.  The “merchandise” cost little in the country of production, and the returns were considerable.

But, necessary as was the foundation of the colonies beyond the sea from all points of view, it could not justify those markets for human flesh.  Generous voices soon made themselves heard, which protested against the trade in blacks, and demanded from the European governments a decree of abolition in the name of the principles of humanity.

In 1751, the Quakers put themselves at the head of the abolition movement, even in the heart of that North America where, a hundred years later, the War of Secession was to burst forth, to which this question of slavery was not a foreign one.  Different States in the North—­Virginia, Connecticut, Massachusetts, Pennsylvania—­decreed the abolition of the slave trade, and freed the slaves brought to their territories at great expense.

But the campaign commenced by the Quakers did not limit itself to the northern provinces of the New World.  Slaveholders were warmly attacked beyond the Atlantic.  France and England, more particularly, recruited partisans for this just cause.  “Let the colonies perish rather than a principle!” Such was the generous command which resounded through all the Old World, and, in spite of the great political and commercial interests engaged in the question, it was effectively transmitted through Europe.

The impetus was given.  In 1807, England abolished the slave-trade in her colonies, and France followed her example in 1814.  The two powerful nations exchanged a treaty on this subject—­a treaty confirmed by Napoleon during the Hundred Days.

However, that was as yet only a purely theoretical declaration.  The slave-ships did not cease to cross the seas, and to dispose of their “ebony cargoes” in colonial ports.

More practical measures must be taken in order to put an end to this commerce.  The United States, in 1820, and England, in 1824, declared the slave trade an act of piracy, and those who practised it pirates.  As such, they drew on themselves the penalty of death, and they were pursued to the end.  France soon adhered to the new treaty; but the States of South America, and the Spanish and Portuguese colonies, did not join in the Act of Abolition.  The exportation of blacks then continued to their profit, notwithstanding the right of search generally recognized, which was limited to the verification of the flag of suspicious vessels.