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John Slidell

1793 - July 9, 1871

Topic- U.S. Election of 1844, Diplomacy

John Slidell was appointed U.S. minister to Mexico by the Polk administration in 1845. Upon his arrival in the country, however, the Mexican government refused to accept his credentials, and he returned home the following year. Polk would cite Mexico’s rejection of Slidell as one of the reasons why the United States had "ample cause of war" in May, 1846.

A native of New York, Slidell graduated from Columbia College in 1810 before moving to New Orleans in 1821, where he practiced law and dabbled in local politics. An ardent Democrat, he served for four years as federal attorney for eastern Louisiana during the Jackson administration. Elected to Congress in 1843, he helped James K. Polk win the state in 1844.

Anger over the pending annexation of Texas had prompted Mexico to break off diplomatic relations with the United States soon after Polk took office in the spring of 1845. By the fall, however, the administration had received word that the Herrera government was prepared to accept a minister from the United States. Anxious to resume diplomatic relations as soon as possible, Polk appointed Slidell, who was fluent in Spanish, while Congress was in recess. Secretary of State Buchanan made it clear in his instructions to Slidell that the settlement of the boundary dispute between the two countries should be his highest priority. To secure Mexico’s recognition of the Rio Grande as the southern boundary, Slidell was authorized to offer to assume the claims of U.S. citizens totaling $3.25 million. In addition, Buchanan instructed his diplomat to explore the possibility of acquiring California and New Mexico, for which the administration was prepared to pay up to $30 million. Upon Slidell’s arrival in Mexico in December, the weak Herrera government, accused by the political opposition of treason for its willingness to negotiate with the United States, refused to accept his credentials. A military coup followed, headed by General Mariano Paredes, whose government also refused to negotiate with Slidell. The diplomat returned to the United States, meeting with President Polk on May 8, 1846. Polk was prepared to send Congress a message asking for a declaration of war on the grounds of Mexico’s rejection of the U.S. minister. The following day, the administration received word of the attack on U.S. forces along the Rio Grande.

Slidell returned to public life in 1853, when he was appointed to the Senate to fill unexpired term. As a senator, he was a strong states rights advocate, and with other southerners voted for repeal of the Missouri Compromise, the acquisition of Cuba, and the admission of Kansas under the Lecompton constitution. Winning re-election, he served until February, 1861, when Louisiana passed the ordinance of secession.

During the Civil War, Slidell accepted a diplomatic appointment to France to seek diplomatic recognition of the Confederacy. During the transatlantic crossing in November, 1861, he and another Confederate envoy, James Mason, were removed from a British ship, the RMS Trent, and arrested by the captain of a Union vessel. The Trent Affair sparked an international incident, prompting the British government to demand an apology. Unwilling to risk war with Great Britain over the incident, the Lincoln administration released the two envoys and disavowed the Union captain's actions, although it refused to issue an apology.

Slidell failed in his objective of achieving diplomatic recognition, though France remained sympathetic to the Confederate cause. Slidell continued to lobby in Europe for his government throughout the war, managing to arrange some loans for the Confederacy from private interests. After the war, Slidell remained in Europe. He died in London, England, on July 29, 1871.


Sears, Louis Martin. John Slidell. Durham: Duke University Press, 1925.

Tregel, Joseph Jr. "The Political Apprenticeship of John Slidell," The Journal of Southern History Vol. 26, No. 1 (Feb. 1960): 57-70.

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