Treaty between the United States and Great Britain for the Suppression of the Slave Trade (Lyons-Seward Treaty of 1862)

By the mid-nineteenth century, efforts to end the transportation of slaves from Africa to various locations in the Western Hemisphere had been underway for decades. In 1807, Great Britain outlawed the slave trade within its empire, with a few exceptions in Asia, and the United States outlawed the importation of slaves in the same year, effective in 1808. In 1862, the United States was involved in the Civil War, a central cause of which was slavery. Great Britain and the United States had just come to an agreement regarding the Trent Affair, which dealt with stopping ships in international waters. Sensing that the time was right for further agreements, the British ambassador, Lord Richard Lyons, proposed to Secretary of State William Henry Seward an agreement that would expand efforts to totally eliminate the slave trade. This included allowing each country the freedom to board and inspect any ships suspected of being involved in the slave trade, not just their own. Within weeks, the two countries agreed, and without any senators from the Southern states, the treaty was quickly ratified.

Summary Overview

By the mid-nineteenth century, efforts to end the transportation of slaves from Africa to various locations in the Western Hemisphere had been underway for decades. In 1807, Great Britain outlawed the slave trade within its empire, with a few exceptions in Asia, and the United States outlawed the importation of slaves in the same year, effective in 1808. In 1862, the United States was involved in the Civil War, a central cause of which was slavery. Great Britain and the United States had just come to an agreement regarding the Trent Affair, which dealt with stopping ships in international waters. Sensing that the time was right for further agreements, the British ambassador, Lord Richard Lyons, proposed to Secretary of State William Henry Seward an agreement that would expand efforts to totally eliminate the slave trade. This included allowing each country the freedom to board and inspect any ships suspected of being involved in the slave trade, not just their own. Within weeks, the two countries agreed, and without any senators from the Southern states, the treaty was quickly ratified.

Defining Moment

The relationship between the United States and Great Britain had fluctuated widely during the almost eighty years since the end of the Revolutionary War, but through the decades, ties had gradually become stronger. Agreements regarding the northern border of the United States and increased trade had brought the two countries into a more harmonious relationship. However, with the secession of the Southern states and the beginning of the American Civil War, the relationship between the two countries again became strained. The supply of American cotton to British mills was greatly diminished, and United States ships were intercepting British freighters as the Union blockade of the South tried to put economic pressure on the Confederates. To strengthen this effort, the American ships that had been patrolling near Africa to block the slave trade were withdrawn to American waters. The November 1861 Trent Affair, in which two Confederate emissaries were taken off the British ship RMS Trent in international waters, also put the British firmly at odds with the American government.

In addition to these elements, the British view of the American secretary of state, William Seward, was highly negative. Seward had been the favorite to become the Republican nominee for president in 1860, but his strongly belligerent views on slavery and other issues diminished support for him, and the more moderate Abraham Lincoln was nominated. When Seward and others were convinced to take steps to relieve the tension with the British over the Trent Affair, the British ambassador to the United States, Lord Richard Lyons, came to change his opinion of Seward. After they had jointly solved one crisis, Lord Lyons pushed forward to address another issue related to the Trent Affair.

Although the international slave trade had been outlawed by most nations, it was still occurring. Based on understandings reached at the end of the War of 1812 and the Trent Affair, British naval officers would be taking a major risk by stopping any American ships in international waters. With the American navy focusing on the blockade in American coastal waters, many slave ships near Africa were flying the American flag to avoid being stopped by the British. Based on the common interest of the United States and Great Britain in ending the illegal slave trade, Lyons proposed a treaty to cooperate in apprehending ships and crews involved in the trade. Seward saw the treaty’s advantage to the United States as well as to his own antislavery views. He and Lyons quickly negotiated the specifics of the treaty, and it was ratified by both countries.

Author Biography

Born May 16, 1801, to Samuel Sweezy Seward and Mary Jennings, William Henry Seward was one of five children in a strong and prosperous household in Florida, New York. He graduated from Union College with a law degree and began practicing law in 1821. He moved to Auburn, New York, to practice law with his fiancée’s father. In 1824, he married Frances Adeline Miller, with whom he had five children. Having grown up in a household with slaves, he understood the inequality of the system. His wife was a strong abolitionist, pushing him further in that direction and opening their home to fugitive slaves.

During the 1830s, Seward entered politics, serving in the state Senate as a member of the Anti-Masonic Party. After losing a race to become governor of New York, Seward traveled throughout the state giving speeches, including one on the need for universal education. He was elected governor in 1838 and 1840 as a Whig. In 1849, he was chosen to be a US senator and led the antislavery wing of the Whig Party. Seward was reelected in 1855 and moved to the Republican Party, as most Whigs did when the Whig Party disintegrated. In 1858, he made a divisive and prophetic speech stating that the American system could not endure the split between slave and free states; he said it would become all one or the other. Seward was favored for the 1860 Republican nomination, and while he had the plurality on the first nominating ballet, his support rapidly dropped. He campaigned for the eventual nominee, Abraham Lincoln, and when Lincoln won the general election, Seward agreed to join his cabinet.

As secretary of state, Seward had an expansionist vision for America. Even during the Civil War, he spoke of expanding not just in North America but into the Pacific Ocean and the Caribbean. This, in addition to his aggressive nature, set him at odds with European leaders, who saw him as intruding into their areas. The most dangerous task that confronted him during the Civil War was the Trent Affair, when he had to work with the British to diffuse a situation that might have led to war with Britain. As this was handled very professionally, Seward’s standing with British leaders increased, and they were willing to negotiate with him on a number of other matters, including ending the slave trade.

After the war, Seward’s only acquisition was the purchase of Alaska. However, he strengthened relations with China and Japan, as well as helping establish a stronger American influence in Hawaii. He retired at the end of President Andrew Johnson’s term of office and traveled widely until shortly before his death on October 10, 1872.

Document Analysis

By 1862, the transportation of Africans to the Americas for the purpose of enslavement had existed for around 360 years. However, since 1836, no country had recognized participation in the international slave trade as a legitimate activity. Although slave trading had declined greatly since the end of the eighteenth century, the continued existence of slavery in several countries and colonies made it a profitable criminal endeavor for those who were willing to risk capture. With one of the major slaveholding countries in the midst of a civil war between the slaveholding and nonslaveholding sections, the opportunity existed to push for further steps to end the exploitation of Africans. Lord Lyons, envoy to the United States from Great Britain, and William Seward, US secretary of state, discussed this issue and drew up an agreement that, within a few years, effectively put an end to the transportation of slaves from Africa to the Americas.

Ever since the Portuguese began the practice in the fifteenth century, European and, later, American powers had sought economic gain via slave labor. However, beginning in the 1800s, slavery and the slave trade began to be examined from a human-rights perspective. As a result, both were slowly outlawed by the major Western powers. However, the legal changes outlawing both practices were not uniform, nor were they implemented at the same time in all places. Thus, as long as slavery was legal, the possibility for slave trade existed. Cuba, which allowed slavery until 1884, was the focal point for the Caribbean slave trade, including shipments to the United States, which were illegal after 1808. With the United States outlawing the participation of its citizens in slave trading between foreign countries in 1800, Great Britain’s similar law in 1807, and the US ban on the importation of slaves going into effect in 1808, the international slave trade did decline. By the end of the 1830s, virtually all other European powers had similar laws, with enforcement varying from country to country. Under various treaties, the British fleet was the principal enforcement mechanism, and it posted numerous ships near the African coast.

In 1842, the United States signed the Webster-Ashburton Treaty, in which the United States promised to establish a fleet off the west coast of Africa to intercept slave ships flying the American flag. When the United States withdrew the ships to assist in the blockade of Southern ports in 1861, many slave ships began flying the American flag in order to avoid being stopped by the British. The British and most Union leaders wanted to end slavery, and they saw a treaty on the slave trade as one step toward that goal. Although the Lyons-Seward Treaty was signed and ratified, none of the Union leaders actually believed that ships were going to run the naval blockade of the South to bring in additional slaves. The last documented group of slaves illegally brought into the United States was in 1859. However, the treaty was a forceful statement of the American government’s vision for the future.

The treaty itself is fairly straightforward, with provisions allowing for the conviction of slave traders even if no slaves were present. This means that anyone sailing a ship equipped to transport slaves was always at risk. Lyons and Seward tried to be as comprehensive as possible in drawing up the provisions under which a ship could be seized for participating in the slave trade. The opening of the treaty follows the traditional formulation of treaties by describing the nations involved and giving the credentials of those making the agreement. In line with the tradition established by President George Washington, references to the United States and its leaders are very simple compared to the British embellishments.

Having established the credentials of the negotiators, the twelve articles of the treaty outline three basic areas of agreement: who is authorized to undertake searches, the legal procedure for searches for evidence (including what constitutes evidence), and the adjudication of the treaty through “mixed courts of justice.” Article 1 of the treaty begins with a statement reflecting these three themes of the treaty, as well as introducing the reason for the treaty’s existence. The treaty “for the Suppression of the Slave Trade,” as the formal title states, applies to the use of “their respective navies” to undertake the task. If a commercial vessel were suspected of having “been engaged in the African slave trade,” then, as would be expected from democracies, the accused would “be brought to trial” and a verdict issued by a court. This summation of the treaty is then clarified throughout the remainder of the document, as well as through two annexes to the treaty, negotiated simultaneously with the formal treaty.

As to the first general principle of the treaty–who was authorized to undertake the mission to stop the slave trade–the ships authorized to undertake this mission are described in articles 1 and 2, as well as in annex A. In order for the goal to be reached, ships from either navy could stop commercial vessels from either country to inspect for signs of slave trading. (Prior to the treaty, only British naval vessels could stop British ships and American naval vessels, American ships.) However, in order to reduce any problems that might arise from possible interference with legitimate commercial enterprises, the treaty limits the scope of the search for slave traders in several ways. The first is by giving this task not to the whole navy but only to certain ships. Thus, as stated in article 1, only ships “authorized expressly for that object” were to undertake operations against suspected slave ships. The ship to be stopped had to be a private vessel; official (i.e., naval) ships of either country could not be stopped. In addition, the fourth section of article 1 delimits the geographical areas in which ships were subject to being searched. The northern border of the African search area was the thirty-second parallel north, which cuts approximately through the middle of the current nation of Morocco. Thus, the search area included essentially all the ocean adjacent to the entire west coast of Africa, as well as the area within thirty leagues of Cuba. Due to the success of the patrols, in 1863, the area within thirty leagues of Madagascar, Puerto Rico, and Santo Domingo (Hispaniola) was added to the search area.

In article 2, further clarification is given regarding those who were authorized to enforce the treaty. Naval vessels that were authorized to carry out the mission of stopping the slave trade were to be specifically named by their respective governments and given copies of the treaty, as well as the two annexes. While this would not be important when stopping a ship from their own country, having the document that authorized stopping a foreign ship would make discussions with the captain of the merchant ship easier. Naming specific ships made it easier to coordinate efforts. Section 2 of article 2 provides that ships assigned to this mission have as commander a person with at least the rank of lieutenant.

In annex A, not printed in this text, specific directions are given for the boarding of a ship suspected of participating in the slave trade. Anyone up to the commander of the naval vessel stopping the merchant ship could be part of the boarding crew. However, annex A tries to give assurance that a senior officer will participate in boarding the suspected ship and overseeing the search for evidence, stating that at least a lieutenant should be in charge of the boarding crew, or if the officer corps on board were depleted, then at least the “second in command of the ship” should participate in the search.

Most of the treaty deals with the procedure by which the search, and any evidence found, would be documented. This second aspect of the treaty, the procedure, was the first step to ensure that due process would be carried out in the investigation and in preparations for any possible trial. The third section of article 1 gives specific guidelines on the paperwork necessary when stopping and boarding a merchant ship. The captain of the naval vessel was to give a copy of his orders showing he was “authorized to search” to the captain of the merchant vessel. When someone other than the captain of the naval vessel did the actual boarding and search, this other officer also had to complete paperwork documenting his role in the action. This was to provide documentation regarding evidence to be used in any trial and to ensure that any innocent ship that was stopped had the necessary documents to explain its delay in transit and to make certain it was not stopped and searched by any other naval vessel. As previously mentioned, the treaty expresses a preference for an officer with at least the rank of lieutenant, with provisions for an exception in the unusual circumstance that no one with that rank or above was available. In order for the system to work correctly, the treaty states that the naval commanders should “adhere strictly to the exact tenor of the aforesaid instructions.”

Annex A also states that the search was to “be conducted with the courtesy and consideration which ought to be observed between allied and friendly nations.” Under provisions in article 2, if any ship in a convoy were suspected of being a slave ship, then the entire convoy would be stopped and the commander of the convoy would be allowed to participate in the search, along with the naval officials and the commander of the suspected ship. If nothing was found, then the ship would, as article 1 states, “be left at liberty to pursue its voyage.” However, if sufficient evidence was found to cause the boarding party to take the merchant ship to be tried in court, three potential locations were given for this to happen. The naval commander was charged to take the merchant ship to the nearest or most easily reached court. Annex A gives stipulations as to how the merchant ship should be crewed during the trip to court. The merchant ship, and everyone and everything on it, was to be taken to the port, where a court could make a final ruling on the guilt or innocence of the captain and crew. It also directs the individual in charge of the search to draw up a document listing all the papers, people, and cargo found on the merchant ship.

As for the evidence necessary for the naval vessel to take the merchant ship to a court of justice, the most obvious piece of evidence would be Africans found on board en route to the Americas. However, as that was only possible on the westbound voyage, article 6 of the treaty lists ten items that were commonly identified as being integral to the slave trade. Thus, items such as “hatches with open gratings” or “a greater number of mess-tubs or kids than requisite for the use of the crew” could constitute enough evidence to take a ship into custody. As with many legal cases, there could be gray areas, such as how many mess-tubs a crew might need. This was the type of question for the court to rule on; a naval officer finding any of these items, or large enough quantities to raise questions, would be authorized to take possession of the merchant ship.

The “mixed courts of justice” were considered “mixed” because judges from both countries jointly presided at the trials. Annex B gives directions for the trials in line with its title, “Regulations for the Mixed Courts of Justice.” Assuming that all the procedures had been correctly followed and one or more of the suspicious items listed in article 6 were found, even if a merchant captain and crew were found innocent, then there would be no compensation for the merchant or those shipping cargo on the vessel. However, if none of the suspicious items were found, then the naval officer and the nation that he served would be liable to pay compensation for delay and damages.

If the merchant captain and crew were found guilty of participating in the slave trade, then they were to be punished by the country whose flag they flew. Since both the United States and Great Britain had been signatories to an agreement to charge slave traders as pirates, the punishment would be similar. The ship itself would be destroyed, although provision was made for it to be purchased by one of the governments if it “should wish to purchase her for the use of its navy.” Any cargo, except for persons from Africa being taken into slavery, became the property of the government whose flag the merchant vessel was flying. If it could be clearly proved that those shipping cargo on such a ship did not know of it being used for the slave trade, then they could get their cargo returned. The Africans on board a captured ship would “be immediately set at liberty, and shall remain free, the Government to whom they have been delivered guarantying their liberty.” If Africans were found on board a slave ship, it might not be possible for them to be returned to their homes; however, the two countries did give the strongest assurances possible that those who might have become slaves would at least regain their freedom. The strength of the treaty lay in the fact that what might have been called circumstantial evidence in other cases was defined in the treaty as “primâ facie evidence” that the vessel was employed in the African slave trade.

Essential Themes

The Treaty for the Suppression of the Slave Trade was written in such a way as to follow as closely as possible the normal procedures of international law at the time. It includes provisions for compensation for those unjustly detained. However, the two countries’ intent to end the slave trade could be seen in the list of prima facie evidence for conviction, which goes far beyond just finding chained Africans on board. The fact that shackles or extra sleeping mats could convict a slave trader made engaging in the slave trade a much more greater risk. While that could be avoided by stripping the ship when the slaves were sold and then reinstalling everything in the African port when new slaves were purchased, doing so negated the profits. As a result of this treaty, the transatlantic African slave trade finally came to an end. Although slavery lasted until the 1880s in Cuba and Brazil, there is no record of any people brought from Africa after the 1860s. The new era of closer US-British relations, which had started with the peaceful conclusion of the Trent Affair, was strengthened by the cooperation established by this treaty, often called the Lyons-Seward Treaty. These two individuals, who at the beginning of Abraham Lincoln’s presidency seemed to be as far apart as their homelands, became effective partners in developing a close alliance. Even though there was still a long way to go toward full equality of all peoples, the successful suppression of the slave trade was a landmark on that path.


  • “British-American Diplomacy: Treaty between United States and Great Britain for the Suppression of the Slave Trade; April 7, 1862.”Avalon Project. Lillian Goldman Law Lib., 2008. Web. 18 Apr. 2013.
  • Goodwin, Doris Kearns.Team of Rivals: The Political Genius of Abraham Lincoln. New York: Simon, 2005. Print.
  • Jenkins, Brian. “The ‘Wise Macaw’ and the Lion: William Seward and Britain, 1861–1863.”University of Rochester Library Bulletin 31.1 (1978): n. pag.River Campus Libraries: University of Rochester. Web. 18 Apr. 2013.

Additional Reading

  • Ferris, Norman B.Desperate Diplomacy: William H. Seward’s Foreign Policy, 1861. Knoxville: U of Tennessee P, 1976. Print.
  • Foreman, Amanda.A World on Fire: Britain’s Crucial Role in the American Civil War. New York: Random, 2010. Print.
  • Hill, Walter B., Jr. “Living with the Hydra: The Documentation of Slavery and the Slave Trade in Federal Records.”Prologue 32.4 (2000): n. pag.National Archives and Records Administration. Web. 18 Apr. 2013.
  • Jones, Howard.Abraham Lincoln and a New Birth of Freedom: The Union and Slavery in the Diplomacy of the Civil War. Lincoln: U of Nebraska P, 1999. Print.
  • Stahr, Walter.Seward: Lincoln’s Indispensable Man. New York: Simon, 2012. Print.
  • Taylor, John M.William Henry Seward: Lincoln’s Right Hand. New York: Harper, 1991. Print.
  • “Timeline of Atlantic Slave Trade.” ABC News, 2 July 2000. Web. 18 Apr. 2013.
  • Van Deusen, Glyndon G.William Henry Seward. New York: Oxford UP, 1967. Print.