The Trent Affair’s Diplomatic Winners and Losers

November and December 2021 mark the 160th anniversary of the Trent affair. Centered around Confederate diplomatic legitimacy, it caused controversy and embarrassment for the United States, the Confederacy, and United Kingdom, with some surprising winners and losers.

USS San Jacinto intercepts RMS Trent.
NH 73990, Navy History and Heritage Command.

In the fall of 1861, Confederate President Jefferson Davis appointed James Mason and John Slidell as representatives to the United Kingdom and France respectively. They, along with Slidell’s family and two secretaries, escaped Charleston on the blockade runner Theodora, travelling to Nassau and Cuba, where they boarded the British Royal Mail Steamer Trent for passage to Europe.[i] Learning the Confederate plan, famed naval explorer Captain Charles Wilkes patrolled Trent’s anticipated route, intercepting the vessel on November 8, 1861.

Naval aspects of international law impacted things. Trent was British-flagged, carrying British mail and Confederate representatives. Diplomats were often exempt from capture, but the Confederacy remained unrecognized with only belligerent status granted by Queen Victoria. Whether the diplomats, or Trent itself, could be seized was the question. The general consensus internationally was that if Mason and Slidell were found on a foreign ship, that vessel could be seized and brought “to a port of the United States for adjudication by a Prize Court,” but US warships would “have no right” to seize only the commissioners, allowing the vessel they traveled on to freely “continue her voyage.”[ii]

Captain Charles Wilkes, USN.
NH 119637, Navy History and Heritage Command.

Captain Wilkes ultimately bungled the legal fine line. His sailors boarded and temporarily detained Trent, but the mail steamer’s master refused to turn over passenger manifests or allow a search of the vessel. Mason, Slidell, and their aides and baggage, were identified and forcibly transferred, amid protests from Trent’s master, Slidell’s family, and the vessel’s mail agent – a Royal Navy officer.

There were Confederate diplomatic letters of instruction on Trent, but when Mason and Slidell were taken, those documents were hastily and secretly transferred to others. If Wilkes’ sailors had completed a search of Trent and found these, he would have had more justification in condemning and seizing the mail steamer. Instead, “no passports or papers” from the Confederate government were seized and Trent was allowed to go free because Wilkes did not wish to impede innocent passengers, nor did he have the manpower to safely operate both a seized Trent and his own San Jacinto.[iii] By failing to condemn and instead releasing Trent, Wilkes inherently acquiesced that Trent violated no international laws, and thus the Confederates taken were not subject to seizure either.

A firestorm erupted over Captain Wilkes’ actions. British legal scholars declared the removal of Mason and Slidell “illegal and unjustifiable,” while businessmen barked for war against the United States, hoping that Confederate recognition would provide guaranteed bolstering to the island nation’s textile mills.[iv]

Political Cartoon of the Trent affair. Left is British Foreign Secretary John Russell, on Trent are Confederate envoys James Mason and John Slidell, and near the eagle is US Secretary of State William Seward. Jefferson Davis is on the far right.
Library of Congress.

While British politicians debated responses, military officers planned for potential war. Admiral Sir Alexander Milne’s naval squadron was directed to ensure “the safety of her Majesty’s possessions in North America,” and 10,000 regulars were dispatched to reinforce Canada.[v] British diplomats and military leaders even halted sending communiques across the isthmus of Panamá, lest the US-operated Panama Railroad Company seize them. The British War Secretary boasted his forces would “iron the smile” off the United States if war sparked.[vi]

As British outrage grew, Mason and Slidell were confined at Fort Warren, in Boston Harbor. Wilkes was praised for his “great public service” in stopping the Confederates, but many across the United States also speculated about war.[vii] It was a conflict neither side wanted. The US had its hands full with internal rebellion and the potential for a blockade of the Atlantic seaboard worried many, while UK leaders were wary of a costly and lengthy conflict risking their North American colonies and their advantages over a resurging France.

Prince Albert of the United Kingdom.
National Portrait Gallery, United Kingdom.

Britain officially condemned Charles Wilkes’ actions, demanding an apology. Thanks to efforts from Prince Albert, Queen Victoria’s dangerously ill husband, a door was left open for calming. Ambassador to Britain Charles F. Adams insisted Captain Wilkes’ action “was not done by the authority of the [US] government.”[viii] Prince Albert jumped at this opening, convincing British Foreign Secretary Earl Russell and Prime Minister Lord Palmerston that their official demand should include “the restoration” of Mason and Slidell “and a suitable apology” for Wilkes’ unauthorized actions.[ix] Abraham Lincoln and Secretary of State William Seward painstakingly debated the appropriate response. An apology would admit US guilt. The wrong response, or lack of one, could trigger war.

Lincoln and Seward used Prince Albert’s opening and ultimately decided on partial appeasement. Seward dispatched a letter to Britain, admitting Wilkes acted “without any direction or instruction,” acquiescing that he should have seized Trent for adjudication in a prize court, and ordering Mason and Slidell “cheerfully liberated.”[x] The letter however, did not include an official state apology. Not wishing to start an intercontinental war, Earl Russell and Prime Minister Palmerston acquiesced to the de facto apology in the release of the Confederate diplomats. Prince Albert never saw this easing of tensions, passing away twelve days before the US reply was written.

Claiming a diplomatic victory, James Mason and John Slidell reached Europe in early 1862, where they fought for Confederate recognition. At the insistence of Seward and Lincoln, Captain Wilkes was appointed to command the West India Squadron with the rank of acting rear admiral, possibly because of his handling of the Trent affair. Wilkes continued the trend of upsetting foreign powers in that capacity however, and was relieved in 1863 and court martialed into retirement a year later. William Seward continued as secretary of state for the remainder of Lincoln’s administration, as well as that of Andrew Johnson. Earl Russell rose to become Britain’s Prime Minister, replacing Lord Palmerston after that leader’s death.

The Trent affair was the closest the UK and US came to blows during the Civil War. It was a conflict neither party wanted and the question of Confederate diplomats was ultimately resolved with US and British leaders dodging potential conflict. Many point to it as a major what-if of the Civil War, and a British declaration of war could have had major repercussions. Instead, it fizzled out, especially considering Lincoln’s Emancipation Proclamation a year later guaranteed Britain would never ally itself with the Confederacy. For the British, honor was satisfied enough to prove their empire could flex its muscles against foreign challenges. For the United States, it successfully de-escalated potential war with the world’s premier naval power while simultaneously defending the Monroe Doctrine’s claim of US hegemony of the Americas. The ultimate loser in the Trent affair was the Confederacy. Even though their commissioners were released, a political victory that demonstrated their quasi-legitimacy, neither convinced foreign governments to recognize the fledgling country.


[i] Slidell, Mason, Eustis, and Macfarland to Wilkes, November 9, 1861, Letters Received by the Secretary of the Navy from Captains [Captain’s Letters], 1805-61, 1866-85, M125, RG 260, US National Archives.

[ii] The Law Offices of the Crown to Earl Russell, November 12, 1861, James P. Baxter, ed., “Papers Relating to Belligerent and Neutral Rights, 1861-1865”, The American Historical Review, Vol. 34, No. 1 (Oct 1928), 85.

[iii] Wilkes to Welles, November 15, 1861 and Fairfax to Wilkes, November 11, 1861, Captain’s Letters.

[iv] The Law Offices of the Crown to Earl Russell, November 28, 1861, Baxter, ed., “Papers Relating to Belligerent and Neutral Rights, 1861-1865”, 86.

[v] Earl Russell to the Lords Commissioners of the Admiralty, November 30, 1861, Official Records of the Union and Confederate Navies in the War of the Rebellion [ORN] (Washington, D.C.: Government Printing Office, 1880-1901), Series 1, Volume 1, 161; Trevor Cox, The American Civil War and the British Imperial Dilemma, Ph.D. Thesis, University of Wolverhampton, UK, January 2015, 111-112.

[vi] Lewis to Twisleton, December 5, 1861, Gilbert Frankland Lewis, ed., Letters of the Right Hon. Sir George Cornewall Lewis, Bart. To Various Friends (London: Longman’s, Green, and Co., 1870), 406; Bedford Pim, The Gate of the Pacific (London: Lovell Reeve & Co., 1863), 6.

[vii] Welles to Wilkes, November 30, 1861, ORN, Series 1, Volume 1, 148.

[viii] Charles Francis Adams diary, December 1, 1861, Adams Family Papers, Massachusetts Historical Society, Boston, MA.

[ix] Queen Victoria to Earl Russell, December 1, 1861, Arthur Christopher Benson and Viscount Esher, eds., The Letters of Queen Victoria: A Selection of Her Majesty’s Correspondence Between the Years 1857 and 1861, Vol. 3 (London: John Murray, 1911), 470.; Norman B. Ferris, “The Prince Consort, ‘The Times,’ and the ‘Trent’ Affair”, Civil War History, Vol. 6, No. 2 (June 1960), 153.

[x] Seward to Lord Lyons, December 26, 1861, ORN, Series 1, Volume 1, 179, 187.

13 Responses to The Trent Affair’s Diplomatic Winners and Losers

  1. In the article above Mr. Chatelain says of the Trent Affair: “Many point to it as a major what-if of the Civil War, and a British declaration of war could have had major repercussions. Instead, it fizzled out, especially considering Lincoln’s Emancipation Proclamation a year later guaranteed Britain would never ally itself with the Confederacy.”

    He is right to say it was a “major what-if,” but not for the reason he thinks. Nor did it fizzle out because the Emancipation Proclamation kept Britain from allying with the South. There is good evidence that Jeff Davis sent diplomats Mason and Slidell to France and Britain with an offer to end slavery in exchange for their support in the Confederacy’s war for independence.

    A British paper called “Once A Week,“ dated Nov. 30, 1861, states the following: “Slavery is doomed, on any supposition; and the Confederate authorities are already saying publicly that the power of emancipation is one which rests in their hands; and that they will use it in the last resort. This is a disclosure full of interest, and hope.” Here we see that the CSA has declared an end to slavery as an option if it will mean CSA independence. Here we see that independence rather than slavery was the motive for Southern secession and its willingness to fight for independence.

    After being illegally held prisoner by the Union, Mason and Slidell were released to the British and given transit on a British ship to England, arriving January 29, 1862. On that same day the anti-South abolitionist newspaper The Spectator announced:

    “It is understood, in that indirect but accurate way in which great facts first get abroad, that the Confederacy have offered England and France a price for active support. It is nothing less than a treaty securing free trade in its broadest sense for fifty years, the complete suppression of the import of slaves, and the emancipation of every negro born after the date of the signature of the treaty.”

    The paper attributes the authorization of the offer to end slavery as coming from “a promise made by a Mississippian,” an obvious reference to CS President Jefferson Davis. Does it make sense now why the Union was willing to risk war with Britain to stop the mission of the CS diplomats who were bringing that promised offer?

    The Spectator would not be the only foreign paper reporting the highly secretive offer. On April 8, 1862 the “South Australian Register” would echo the report in The Spectator. Later, in “The Daily British Colonist,” May 29, 1862, we read: “The rumors of interference by France and England in American affairs are received, and it is even asserted that the South, in return for the intervention, will guarantee the emancipation of her slaves.”

    It is interesting to note that as a result of this 1862 offer to end slavery, France agreed to ally with the CSA if Britain would also, and sent a French diplomat to Britain to lobby for an alliance. The only reason Britain did not was because, according to the same article in The Daily British Colonist:

    “The proposition for intervention comes from France…. The ‘Independence Belge’ asserts that the object of Lavulette’s recent visit to England was to induce England to consent to a common intervention in American affairs. England agreed on condition that the Roman question be first settled.”

    What was this “Roman question?” There was an issue occurring in Rome involving occupation of Papal lands by French troops that Britain was afraid might escalate into a European conflict. The Brits did not want to involve themselves in the American conflict until this “Roman question” was resolved. Unfortunately for the CS, the issue was not resolved until 1871, and not fully resolved until the Lateran Treaty of 1929.

    From these foreign reports we find out what most likely was the nature of the mission of the Confederate diplomats illegally taken on The Trent. But confirmation of the mission does not stop there. On July 15, 1862, we find even stronger evidence from a domestic source. Seven Union loyal border State Congressmen write emphatically in a letter to Lincoln that the CS offer to end slavery is reality:

    “We are the more emboldened to assume this position from the fact, now become history, that the leaders of the Southern rebellion have offered to abolish slavery amongst them as a condition to foreign intervention in favor of their independence as a nation. If they can give up slavery to destroy the Union; We can surely ask our people to consider the question of Emancipation to save the Union.” (Abraham Lincoln Papers at the Library of Congress: Series 1. General Correspondence. Border State Congressmen to Abraham Lincoln,Tuesday, July 15, 1862)

    These seven Union loyal border State congressmen had no reason to lie or spread mere rumor to their President in affirming the CS offer to end slavery as a “fact now become history.” Especially during a time of war. It must be asked then: Is it mere coincidence that Lincoln had just met with these border State congressmen on July 12, 1862, and the very next day he drafted his own plan of emancipation with which he surprised Seward and Welles? For so long Lincoln had resisted demands for Executive action regarding emancipation, especially if there was no colonization plan in place and ready to rid the country of, in Lincoln’s words, “the troublesome presence of free negroes.” Lincoln’s EP was a direct response to the offer of emancipation by the CSA. He was attempting to head off that offer.

    Mr. Chatelain speculated that Lincoln’s EP “guaranteed Britain would never ally itself with the Confederacy.” Perhaps it had an impact, but more likely it was “the Roman Problem” that held up British alliance with the CSA as the French and Belgian papers reported. And Mr. Chatelain’s “major what-if” isn’t what he thinks. Had the CSA offer to end slavery in January 1862 been accepted by the Brits, there would have certainly been a CSA victory in a significantly shorter war, no subsequent Reconstruction with Republican antics to deliberately divide the races for political advantage in the South, and no resulting Jim Crow that led to another one hundred years of black oppression. But instead we got Lincoln’s war of cupidity, and destitution for both Southern blacks and whites because he had no plan for the freed people other than “root hog or die,” and the deliberate destruction of the South’s economy along with forcing all Southerners to give up their founding birthright of a ‘government by consent of the governed.’

  2. In the not-so distant past, it was often joked in the American Midwest that, “interfering with the Mail was a Federal offense.” And the punishment for stealing your neighbor’s mail could be draconian, with potential for significant jail time. Then, the U.S. Postal System was privatized, and the stigma of interfering with the mail (and parcel delivery) gradually disappeared.
    We tend to lose sight that the Mason & Slidell Affair involved a steamship under contract to transport Queen Victoria’s personal letters; and deliver Official dispatches of Her Majesty’s Government. The fact that commoners also availed themselves of the Royal Mail service was an ancillary function; but a commoner’s mail enjoyed the same State protection during transport as The Queen’s letters.
    And it is my understanding that a Royal Mail Steamer enjoyed roughly equal protection and status as a Government Embassy: mess with it at your peril; war may result.
    So, the Trent Affair was sparked by Captain Wilkes; and a show of British indignation (and the release of Mason and Slidell) resulted. But, something generally overlooked also took place: protection of U.S. Mail steamers. The Confederate Government observed the movement of Steamships operating San Francisco to Panama, and Panama to New York with envy, knowing that the gold dug out of California, valued in millions of dollars, was being transported aboard those vessels. But the Trent Affair had confirmed the inviolate nature of the Mail System; and a sharp rebuke by Britain for interfering with ANYONE’S mail could be expected (with permanent loss of opportunity to gain Official recognition of the Confederate States of America the result.) (In addition, armed troops began riding aboard the U.S. Mail steamers, offering a significant counter to Rebel piracy – see Chatelain “Controlling the California Gold Steamers: The Panama Route in the U.S. Civil War” (2017).) So, the regular gold shipments from California persisted during the course of the war.

    1. Thanks for making the mail steamer connection. The more I dig into the role and participation of the U.S. mail steamers in the war, the more I am fascinated by this largely unthought of element that ties together economics, diplomacy, international law, naval warfare, and politics.

  3. I know “enough” to appreciate the nuances of the international maritime laws. I fully understand Captain Wilkes’ thinking when he captured the two Confederate emissaries while allowing the British flagged ship to proceed. I am sure he thought he would be inviting more trouble for himself and his country if he seized the ship.

    1. You bring up a fairly valid thought. I mention that Wilkes did not want to impede neutrals in the write up, thus he released Trent. He also was likely weighing fallout from capturing a British-flagged ship. Though legally he might have had more justification to seize Trent, along with the Confederate diplomats, this would likely have created even more backlash among commoners across Britain.

  4. William Seward thought he could run bumpkin Abraham Lincoln and advocated war in Mexico over French interference there as a way to unify America. Think Karl Rove’s war strategy to save bush, jr.’s reelection after 9/11/2001. Lincoln’s response was, “One war at a time.” A principle he adhered to in backing down on the Trent affair and releasing the rebel “diplomats.” The genius of Abraham Lincoln in practical effect.

  5. Lincoln offered to go to War with Great Britain, unless they stopped building Confederate ships that were going to be used for raiding Union commerce.. They stopped building those ships.

    I never put much belief or truth in Great Britain ever coming to the relief of the South.

    1.The distance between Great Britain and North America had increased since 1776.

    2. Palmerston had been informed by his Generals that the forts along the US-Canadian border had fallen into dis-repair.

    3. How was Great Britain going to supply an army in Canada when the St Lawrence River froze during the winter?

    4. While both navies had ironclads, the US ironclads could navigate rivers while the Great Britain ironclads could not.

    5. There was an entire segment of the US population that would have enlisted just to fight Great Britain…that segment was known as the Irish. And when the US defeated Great Britain one of the results would have been a free and united Ireland.

    6. In 1860 Great Britain had to import food in order to feed its population. As we know form World Wars 1 and 2, this was a weakness. In 1860, Great Britain imported up to 50% of it’s food for consumption, from the United States. You can’t eat cotton. But you can eat American corn and American wheat. Recall that food rationing persisted in Great Britain 9 years after the end of World War 2.

    7.Great Britain had a great financial interest in Northern railroads.

    8. While the elite was still smarting from the defeat in 1781, the workers in Great Britain realized early on that the was was one of wage labor vs slave labor.

    9. No matter how Palmerston felt, he had to get the approval of the Queen, in order to think about starting a war.

    10. He could not get a bill passed through Parliament declaring war on The US.

    11. At the same time of the US Civil War, Great Britain warned Prussia not to get involved in the affairs of Denmark. Palmerston declared that the British would intervene if Prussia invaded Denmark. When Prussia did invade, Great Britain did nothing.

    12. While Palmerston did say that Great Britain had permanent interests, and not permanent friends, that permanent interest was not cotton. If one reads the speech he gave, he did not mention at all that interest. But in the paragraph preceding and after that comment, Palmerston had addressed the Russian suppression of the Warsaw revolt of 1848. The permanent interest was the British foreign policy of not allowing a European state to have more power than Great Britain.

    13. To rid the constant US threat of invading Canada when Great Britain had a disagreement with the US, Canada became an independent country in 1867.

    The British were not going to do anything. And they didn’t!

    1. when did LIncoln offer ” … to go to War with Great Britain, unless they stopped building Confederate ships that were going to be used for raiding Union commerce?”

      1. It was the development of the Laird rams which alarmed the Union.

        In 1863, the Union found out that Great Britain was constructing 2 ironclads at the Laird shipyards. They were warships. They were made to sever the Union blockade and attack Union coastal cities.

        In September, 1863, Lincoln sent a message through his ambassador the Great Britain, Charles Adams, that is these rams were allowed to leave British ports, it would be war.

        Unknown to the Union , was that Great Britain came to the same conclusion, and bought the rams 2 days before Adams delivered the ultimatum.

        The British realized that a war with the United States did more harm for them, than good.

  6. thanks, great essay … Wilkes was definitely a “loose cannon” in Navy circles … famous for leading the U.S. Exploring Expedition from 1838-1842 charting the South Pacific, Antarctica and the Pacific Northwest … but, infamous as well as he was court martialed twice — the first time in 1843 after the expedition and again in 1864 after a tiff with SECNAV Wells … so, it’s not a surprise he snatched Mason and Slidell off the TRENT in violation of international and admiralty law.– that’s vintage Wilkes.

    Agree with your point on Britain not recognizing the CSA after the Emancipation Proclamation … with their Skavery Abolition Act of 1833, there was no way they would recognize a slave holding republic after the United States’ declaration in 1863.

  7. Thank you for explaining this. When the Trent Affair came up in other reading, it wasn’t fully detailed or its impact. This helped give me a better understanding of its influence. Thanks!

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