American Civil War: Northern Blockade and the ‘Trent’ Affair of 1861

FROM THE LECTURE SERIES: THE AMERICAN CIVIL WAR

By Gary W. Gallagher, Ph.D., University of Virginia

A formal recognition from Europe, especially Britain, was important for both the Confederates and the Federals. However, the Northern blockade of Union ports did become a source of tension for the United States on the diplomatic front; and the Trent affair of 1861 threatened to disrupt all relations between the two nations. Did the Confederacy win this round then?

A ship at the Washington Navy Yard in 1863.
Britain had approved the Union blockade of Confederacy ships in the 1860s. (Image: Everett Collection/Shutterstock)

Federal Ports Blocked

In 1861, the United States Government had stopped almost all foreign shipping coming into the Confederacy or Confederate shipping going out. This posed legal and political questions that were difficult for the North. European nations issued Proclamations of Neutrality in the late spring and summer of 1861, and Great Britain’s came on May 12. This, in turn meant that the nations had recognized the belligerent status of the Confederacy.

Belligerent Status for Confederacy

In the language of international law, the belligerent status of the Confederacy meant that the South could contract for loans and purchase supplies in neutral countries and exercise belligerent rights on the high seas. In other words, it could commission privateers to prey on United States shipping.

This brought rejoicing in the South and concern in the North because both sides thought that recognition of belligerency was perhaps a prelude to formal diplomatic recognition.

This is a transcript from the video series The American Civil War. Watch it now, on The Great Courses Plus.

Formal Diplomatic Recognition for Confederacy?

When London and Paris looked at what was going on in America, they saw a Confederate nation with a written constitution, with a formal government, with an army in the field, and with a foreign policy. They said that’s a belligerent. And the United States, after all, was blockading the Confederacy.

That also suggested that they were both belligerent. So, it seemed an easy call to the Europeans; it did upset many in the North. Secretary of State William Henry Seward was livid when he heard about this. He even thought of starting a war with Britain.

But it soon became clear that the Europeans did not see belligerency as prelude to foreign recognition. Their Proclamations of Neutrality, in fact, favored the North over the long haul because they constituted official acceptance of the blockade.

According to the international law, a blockade must be effective to be legally binding on neutral nations. But, the Union blockade wasn’t as effective.

England Accepts Northern Blockade

But England did not challenge this. The reason was that as a maritime power, Britain often blockaded its enemies. And Britain always had argued that a blockade was legal if the patrolling ships, which were usually British, of course, made an attempt to prevent neutral ships from moving in and out of the ports of the nation that Britain was opposed to.

To insist that the Union blockade, in fact, cover every Southern port might come back to haunt the British down the road. So, the British accepted that the North was trying to blockade the Confederacy, even if they did not seal every port.

Learn more about what happened at Antietam.

Continuous Voyage Doctrine

Britain also accepted the North’s application of what was called the doctrine of “continuous voyage”, which meant that the United States could intercept ships traveling between neutral harbors if there was evidence that the cargoes were destined eventually to go to the Confederacy.

For example, if a cargo was going from London to Bermuda—two neutral ports—but, in fact, was going to end up in Charleston, that would be considered a “continuous voyage” from London to Charleston, even though there was an intermediate neutral stop. And, therefore, that would be subject to being seized by the United States Navy.

Opposition to Continuous Voyage Doctrine

The British themselves used this notion when they were blockading other countries. They didn’t again want to set a precedent that might come back to work against them.

However, British merchants who wished to trade with the South raised great opposition when the British government did nothing in response to Northern seizures of British cargoes under this doctrine. But their opposition had little effect on British policies.

Learn more about the role US Navy played in the American Civil War.

The Trent Affair

The closest Britain came to war with the North over maritime rights occurred with in November 1861.

An illustration showing the 'San Jacinto' (right) stopping the British steamer 'Trent'.
An illustration shows the San Jacinto (right) stopping the British steamer Trent. (Image: Edward Sylvester Ellis/Public domain)

On 8 November 1861, Confederate commissioners James Mason, a Virginian, and John Slidell, of Louisiana, were bound for Britain and France, respectively, aboard the British ship Trent, when the USS warship San Jacinto, under the command of Captain Charles Wilkes, forced the Trent to stop.

They were about 250 miles east of Havana. Wilkes took Mason and Slidell off the Trent. He had received legal advice to not to do it, as Trent was a British vessel. But Wilkes went ahead and did it, and ended up carrying them to a Northern prison in Boston.

The North at first hailed Wilkes as a great hero. There hadn’t been a lot of good news for the North from the battlefield to this point in the war. Manassas was still a sort of festering sore for many in the North. The House of Representatives voted Wilkes a medal early on.

Trent Affair: Almost Triggering a War

However, England accused Wilkes of perpetrating an act of violence against passengers on a neutral vessel, and reacted quickly and ominously. The British naval squadron in North America was reinforced, 8,000 troops were sent to Canada pending the outbreak of possible fighting with the United States, and Britain demanded an official apology and release of Mason and Slidell.

But, Britain also worried about how vulnerable Canada was to the United States. If the United States had decided, with its enormous armies in place during the civil war, to march against Canada, Britain would have been helpless to stop it. War seemed possible for a tense period, but both sides soon realized it would be against their best interests.

Wilkes had acted on his own, and Seward admitted to the British that the captain’s behavior had been improper. Abraham Lincoln ordered the release of Mason and Slidell and they were released on 1 January 1862, and soon they were on their way to London and Paris.

The crisis had passed. But it would not be the last crisis, nor the closest the Confederacy came to achieving a major diplomatic success.

Common Questions about Northern Blockade and the Trent Affair of 1861

Q: What did the belligerent status mean for the Confederacy?

The belligerent status of the Confederacy meant that the South could contract for loans and purchase supplies in neutral countries and exercise belligerent rights on the high seas.

Q: What was the Trent affair?

On 8 November 1861, USS warship San Jacinto, under the command of Captain Charles Wilkes, forced the British ship Trent to stop near Havana. Wilkes arrested Confederate commissioners James Mason and John Slidell, who were aboard the ship.

Q: How did the Trent affair almost triggered a war?

England accused Captain Charles Wilkes of perpetrating an act of violence against passengers on a neutral vessel, the Trent. Thus, the British naval squadron in North America was reinforced and 8,000 troops were sent to Canada pending the outbreak of possible fighting with the United States. But, Britain was also aware of the might of the US army. Thus both sides realized it would be against their best interests and a war was averted.

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