In December 1860 Seward accepted an appointment to serve as secretary of state in the cabinet of President-elect Abraham Lincoln. While Seward was at first dubious about Lincoln’s political acumen, the two soon forged an effective partnership, and Lincoln later ignored radical Republican calls to remove Seward from office.
Seward spent the early months of his tenure in a desperate effort to preserve the Union and avoid civil war. Hoping to ensure that the precarious border states remained sympathetic to the Union, he cautioned Lincoln against using force during the siege at Fort Sumter in South Carolina. After the start of hostilities and Lincoln’s suspension of the writ of habeas corpus, Seward took it upon himself to see that suspected Confederate sympathizers in the North were arrested and detained.
Seward’s primary concern during the war was ensuring that the nations of Europe offered no aid to the rebellion. During what became known as the Trent Affair, he was instrumental in smoothing over tensions with the United Kingdom after the U.S. Navy seized two Confederate envoys from a British ship. Seward later negotiated the Lyons-Seward Treaty of 1862 with British Ambassador Richard Lyons, which helped hinder the Atlantic slave trade by allowing the U.S. and British navies the right to search vessels that appeared to carry African slaves. Seward also had frequent dealings with French Emperor Napoleon III. While Seward narrowly prevented the French from recognizing the Confederacy, he was unable to stop the emperor from establishing a monarchy in Mexico in 1864.
Near the close of the Civil War, Seward was nearly killed as part of the plot that resulted in Lincoln’s assassination. On the night of April 14, 1865, a former Confederate soldier named Lewis Powell attacked Seward—who was in bed recovering from a carriage accident—and stabbed him multiple times with a bowie knife. Seward narrowly survived the attempt on his life and spent several weeks recovering from wounds to his neck and face.