In November 1861, an international crisis developed when Union Captain Charles Wilkes, in command of the United States war steamer San Jacinto, captured former senators James M. Mason of Virginia and John Slidell of Louisiana en route to England on the British mail steamer Trent. The two men were on a diplomatic mission seeking recognition for the Confederacy, one headed to Great Britain and the other to France. In response to the arrest of Mason and Slidell, the British government demanded an apology and the release of the captives. “It thus appears that certain individuals have been forcibly taken from on board a British vessel, the ship of a neutral power, while such vessel was pursuing a lawful and innocent voyage—an act of violence which was an affront to the British flag and a violation of international law,” wrote Britain’s Foreign Secretary Lord John Russell. “The government of the United States must be fully aware that the British government could not allow such an affront to the national honor pass without full reparation.” Tensions ran high at the prospect of war with Britain.
After several weeks of suspenseful discourse regarding the legality of the incident, the crisis ended when the Lincoln administration agreed to release the prisoners on December 28. Massachusetts Senator Charles Sumner rose in the Senate Chamber on January 9, 1862, in support of the President’s decision, which remained controversial. “Every principle of international law, when justly and authoritatively settled, becomes a safeguard of peace and a landmark of civilization,” he reminded his fellow senators in this featured speech. Sumner laid out an argument demonstrating that American principles and precedents upheld the neutral rights of the seas. “The treaties of the United States with foreign nations are in harmony with this principle,” he argued.
In this speech, Sumner compares the capture of Mason and Slidell to the historical practice of impressment of American seamen by the British. “It cannot be forgotten that, in times past, on this identical point of law, Great Britain persistently held an opposite ground from that which she now takes,” Sumner explained. “In exchange for the prisoners set free, we receive from Great Britain a practical assent, too long deferred, to a principle early propounded by our country, and standing forth on every page of our history.”