The first major slave society to banned the importation of African slaves was 1778 Virginia, Great Britain followed in 1807 and the USA in 1808
In 1810 the British entered into slave trade treaty with the USA, as an attempt to end the Atlantic slave trade. Britain would pay African nations not to trade slaves. In the 1830's these treaties faced opposition for being ineffective. Despite paying what amounted to millions in Pounds from European nations the slave trade continued with 'unabated vigour'(2).
The Webster-Ashburton treaty was negotiated by U.S. Secretary of State Daniel Webster and the Honorable Alexander Lord Ashburton on the British side. The treaty covered boundaries of the US, extradition of criminals and suppression of the African Slave trade. Negations concluded on August 9 1842, ratification advised by the Senate was on August 20 1842, and it was finally ratified by the president on August 22 1842(3 ).
Here is the text of the anti slavery portions of this treaty(4 ).
"The parties mutually stipulate that each shall prepare, equip, and maintain in service on the coast of Africa a sufficient and adequate squadron or naval force of vessels of suitable numbers and descriptions, to carry in all not less than eighty guns, to enforce, separately and respectively, the laws, rights and obligations of each of the two countries for the suppression of the slave-trade, the said squadrons to be independent of each other, but the two Governments stipulating, nevertheless, to give such orders to the officers commanding their respective forces as shall enable them most effectually to act in concert and co-operation, upon mutual consultation, as exigencies may arise, for the attainment of the true object of this article, copies of all such orders to be communicated by each Government to the other, respectively."
"Whereas, notwithstanding all efforts which may be made on the coast of Africa for suppressing the slave-trade, the facilities for carrying on that traffic and avoiding the vigilance of cruisers, by the fraudulent use of flags and other means, are so great, and the temptations for pursuing it, while a market can be found for slaves, so strong, as that the desired result may be long delayed unless all markets be shut against the purchase of African negroes, the parties to this treaty agree that they will unite in all becoming representations and remonstrances with any and all Powers within whose dominions such markets are allowed to exist, and that they will urge upon all such Powers the propriety and duty of closing such markets effectually, at once and forever."