On 8 November 1861, Captain Charles Wilkes intercepted a British mail steamer, the Trent. Instead of hauling the ship, passengers, and crew before a federal magistrate for adjudication, Wilkes took it upon himself to arrest two Confederate diplomats—former U.S. Senators James Mason and John Slidell—and their secretaries. Then he allowed the Trent to proceed. Wilkes clapped the men into prison in Boston and was hailed throughout the North as a hero. After the humiliation of Manassas, the Northern public yearned for a victory. Congress even struck a medal to commend Captain Wilkes for his timely snatch.

The British Parliament and public were outraged. Wilkes’s bold action was an insult to the British flag. All the jingoes of the British popular press (those “penny dreadfuls”) were beating the drums for war with the impudent Yankees. Henry John Temple, Lord Palmerston, the aggressive prime minister, was infuriated. He told his cabinet: “You may stand for this, but damned if I will.” Richard Cobden, a British friend of America, wrote that “three fourths of the House [of Commons] will be glad to find an excuse for voting for the dismemberment of the Great Republic.” The British upper classes hardly needed an excuse to vent their hostility to democracy. The Times of London spoke for the ruling aristocracy when it yearned openly for the downfall of the Union: “[It would be] good riddance of a nightmare. . . . Excepting a few gentlemen of Republican tendencies, we all expect, we nearly all wish, success to the Confederate cause.”

Fortunately for the United States, the newly laid transatlantic cable had gone dead. Thus, there were necessary delays in communication across the ocean. Even so, the British cabinet increased the size of their Canadian garrison, adding another 14,000 redcoats to their force of just 6,400. The British even beefed up their North American naval squadron. War with the United States loomed.

Secretary of State Seward had just a few months earlier recommended to Lincoln a war against all the major European powers as a way to unite the bitterly divided Americans against a common foe. Lincoln had politely dismissed Seward’s plan to “wrap the world in flames” then. And now, he cautioned Seward: “One war at a time.”

At this moment of grave tension and maximum danger for the American republic, a royal intervention saved the day. Prince Albert, Queen Victoria’s respected consort, offered an amended draft of Foreign Minister Lord John Russell’s warlike demand for satisfaction. Under Albert’s draft: “Her Majesty’s Government are unwilling to believe that the United States Government intended wantonly to put an insult upon this country and to add to their many distressing complications by forcing a question of dispute upon us. . . .” Thus toned down, Prince Albert’s generous interpretation of U.S. actions was accepted by the Palmerston ministry. Britain asked only for an apology and the restoration of the interned Confederate envoys. It was to be Albert’s last official act. Within days, the poor prince was dead, the victim of typhoid fever. He had labored for peace between the United States and Britain almost literally with his last breath.

Meanwhile, Massachusetts Senator Sumner lectured Lincoln’s cabinet for four hours on Christmas Day. Sumner, an Anglophile with many well-connected friends among Britain’s elite, spelled out terrible consequences if the United States was drawn into war with Britain at this critical hour. Not only would Southern independence likely be achieved, but the continued existence of the United States itself would be in jeopardy, Sumner warned a somber meeting.

Seward was proving a liability in the middle of the unfolding crisis. The previous year, 1860, when the Prince of Wales had visited the United States, the heir to the British throne and the Colonial secretary, Lord Newcastle, had met then Senator Seward. A leading presidential candidate at the time, Seward informed Lord Newcastle that if he won the office it would be his duty to “insult” Great Britain. Worse, Seward supposedly told Newcastle that the United States planned to annex Canada to compensate for the loss of the slave states should Southerners go ahead with plans for secession.

The story of this astonishingly foolish encounter is recorded in the letters of the United States’s very able minister to Great Britain, Charles Francis Adams. It may well have been exaggerated in Lord Newcastle’s retelling, but it sounds so like the swaggering Seward it is hard to discount it completely. This was, after all, the same man who recommended war with the entire continent of Europe to avoid conflict at home. Influential Britons saw the story as confirmation “that Mr. Seward is an ogre fully resolved to eat all Englishmen raw.” Adams was a rare exception to the general rule in the Lincoln administration of using diplomatic postings to pay off party hacks. Lincoln allowed Seward to play party politics in filling the embassies. But, since Britain was the most important of all posts, and since Lincoln approved Seward’s choice of highly capable Adams for the London post, no real harm was done to the Union war effort.

Lincoln determined to do everything possible to keep peace with Britain. The Confederate agents would be released. The United States would acknowledge that Captain Wilkes acted without authority. And Lincoln would apologize. Seward could not resist giving the British lion’s tail one last jerk. He pointed out that the violation of neutral rights of which Britain now complained was exactly the grounds upon which the United States had gone to war with Britain in 1812! Such tact.

The crisis eased as Mason and Slidell were released. The Union turnabout produced an astonished reaction in Britain. Henry Adams, son of the U.S. minister, wrote that the “current which ran against us with such extreme violence six weeks ago now seems to be going with equal fury in our favor.” And, for friends of the Union, the best part is that Mason and Slidell proved to be terrible choices for the Confederacy as diplomats. Both men were so lacking in tact and so intimately associated with the fire-eaters and slavery expanders that their influence in Britain and France can be said to have been zero.