John Slidell (1793 - 1871) was born in New York City. Although a Northerner, he moved to Louisiana and became a U.S. Congressman and U.S Senator from that state. Prior to the Mexican-American War, Slidell was sent to Mexico, by President James Knox Polk, to negotiate an agreement whereby the Rio Grande River would be the southern border of Texas. With the guidance of Zachary Taylor, U.S. troops were stationed at the U.S./Mexico border, ready to attack upon orders. The Mexican government rejected Slidell's mission, and the United States declared war on Mexico on 13 May 1846.
At the Democratic Convention in Charleston, S.C. in April 1860, Slidell plotted with "fire-eaters" such as Mr. William Lowndes Yancey to defeat the only candidate who could have won the general election, namely, Senator Stephen Arnold Douglas, of Illinois.
During the American Civil War John Slidell was one of the two CSA diplomats involved in the Trent Affair in November, 1861. After having been appointed the Confederate States of America's commissioner to France in September, 1861, he ran the blockade from Charleston, S.C., with James Murray Mason. They then set sail from Havana on the British mail steamer Trent, but were intercepted by the US Navy while en route and taken into captivity.
After the resolution of the Trent Affair, the two diplomats set sail for Europe on January 1, 1862. Slidell stayed in Europe after the Civil War; he died in Cowes, Isle of Wight, England, on July 9, 1871, and is buried in the private Saint-Roman family cemetery at Villejuif, near Paris.
The city of Slidell, Louisiana is named after him. He was the brother of Alexander Slidell Mackenzie, a naval officer who commanded the USS Somers on which a unique event occurred in 1842 off the coast of Africa during the Blockade of Africa. In that incident, three crewmen were hanged after being convicted of mutiny at sea.