The mission's objective was to secure diplomatic recognition and support from the French government, as well as to purchase arms and supplies for the Confederate cause. Slidell sailed from New Orleans in October 1861, accompanied by James Mason, another Confederate diplomat who was being sent to Great Britain.
The Slidell Mission was intercepted by the United States Navy in November 1861, when the Union ship USS San Jacinto stopped the British mail packet RMS Trent and removed Slidell and Mason from the vessel. The incident triggered a major diplomatic crisis between the United States and Great Britain, and brought the two countries to the brink of war.
The United States government eventually released Slidell and Mason after pressure from the British, but the Slidell Mission had failed in its primary objective of securing French support for the Confederacy. France never officially recognized the Confederate States of America, and the Confederate government was forced to continue fighting the war without the support of a major European power.