On November 8, Captain Charles Wilkes of the U.S.S. San Jacinto, a fifteen-gun war steamer, took matters into his own hands and, unbeknownst to higher military or political Union officials, ordered the Trent to stop.  After the British ship complied, Wilkes’s lieutenant, Macneil Fairfax, and his men boarded it and removed Mason and Slidell, who were placed under arrest as prisoners of war.  Fairfax then convinced Wilkes to allow the Trent—which was not a blockade-runner, but a mail packet on its regular route—to continue its voyage.  The capture of the Confederate diplomats precipitated one of the major diplomatic crises of the Civil War, known as “the Trent affair.”  The immediate public reaction in the North was jubilation.  Newspapers applauded the action, the U.S. House of Representatives passed a resolution commending Wilkes and awarding him a gold medal, and Navy Secretary Gideon Welles called the captain a hero. 

The British, however, reacted hostilely to an action they considered to be a violation of their neutrality rights under international law (the same rights the British had violated before the War of 1812).  On November 28, the day after learning of the news (there was no transatlantic cable at the time), Lord Henry Palmerston, the British prime minister angrily informed his assembled cabinet, “You may stand for this but damned if I will!”  The others shared the prime minister’s heated sentiments.  On November 30, Foreign Minister Lord John Russell drafted a message to Lord Lyon, the British minister to the United States, directing him to demand an apology from the Lincoln administration for its violation of international law, and the prompt release of the prisoners to British custody, or Britain would cut off diplomatic ties with the United States.  The same day, Britain’s Atlantic fleet was put on alert, and plans were made to send 8000 troops to Canada.  War between Britain and the United States appeared imminent.

The drafts of the intended diplomatic correspondence to the Lincoln administration were sent to Queen Victoria.  Heeding the advice of her dying husband, Prince Albert, the Queen requested that the dispatch include the hope that Wilkes had acted without the knowledge or approval of the Union government or military superiors, and that the United States had not intended to insult the British.  That gave the United States an option to save face diplomatically while still meeting British demands for restitution.  Prime Minister Palmerston readily accepted the changes, and the letter was sent, reaching the United States on December 18.  By that time, American officials were having serious second thoughts about the capture of Mason and Slidell, and the dangerous diplomatic crisis that it had provoked.

To date, President Lincoln and Secretary of State William Seward had not publicly remarked on the Trent affair (the topic was even absent from Lincoln’s annual message to Congress of December 3).  Lincoln’s cabinet met on Christmas morning to discuss the tense situation, at which time Seward presented a draft explaining why international law dictated the release of the Confederate diplomats.  The dispatches from the British and French governments were read (the French supporting the British position), and Senator Charles Sumner, chairman of the Senate Foreign Relations Committee, was called in to read letters from leading British supporters of the Union, which urged release.  Attorney General Edward Bates argued that war with Britain would end any reasonable chance of suppressing the Confederate rebellion.  President Lincoln agreed with the consensus, leaving it to Seward to finesse the release without offending Congress or American public opinion.