Powers of Europe, when
restoring Peace to Europe, with one common interest, will crown this
great work by interposing their benign offices in favour of those
Regions of the Globe, which yet continue to be desolated by this
unnatural and inhuman traffic."[15] Meantime additional treaties were
secured: in 1814 by royal decree Netherlands agreed to abolish the
trade;[16] Spain was induced by her necessities to restrain her trade to
her own colonies, and to endeavor to prevent the fraudulent use of her
flag by foreigners;[17] and in 1815 Portugal agreed to abolish the
slave-trade north of the equator.[18]

68. ~Action of the Powers from 1814 to 1820.~ At the Congress of Vienna,
which assembled late in 1814, Castlereagh was indefatigable in his
endeavors to secure the abolition of the trade. France and Spain,
however, refused to yield farther than they had already done, and the
other powers hesitated to go to the lengths he recommended.
Nevertheless, he secured the institution of annual conferences on the
matter, and a declaration by the Congress strongly condemning the trade
and declaring that "the public voice in all civilized countries was
raised to demand its suppression as soon as possible," and that, while
the definitive period of termination would be left to subsequent
negotiation, the sovereigns would not consider their work done until the
trade was entirely suppressed.[19]

In the Treaty of Ghent, between Great Britain and the United States,
ratified February 17, 1815, Article 10, proposed by Great Britain,
declared that, "Whereas the traffic in slaves is irreconcilable with the
principles of humanity and justice," the two countries agreed to use
their best endeavors in abolishing the trade.[20] The final overthrow of
Napoleon was marked by a second declaration of the powers, who,
"desiring to give effect to the measures on which they deliberated at
the Congress of Vienna, relative to the complete and universal
abolition of the Slave Trade, and having, each in their respective
Dominions, prohibited without restriction their Colonies and Subjects
from taking any part whatever in this Traffic, engage to renew
conjointly their efforts, with the view of securing final success to
those principles which they proclaimed in the Declaration of the 4th
February, 1815, and of concerting, without loss of time, through their
Ministers at the Courts of London and of Paris, the most effectual
measures for the entire and defini