SLIDELL, John, statesman, born in New York city about 1793; died in London, England, 29 July, 1871. He was graduated at Columbia in 1810, and engaged unsuccessfully in commerce. He then studied law, and in 181.9 removed to New Orleans, where, making a specialty of commercial law, he soon acquired a large practice. In 1828 he was a defeated Democratic candidate for congress, and actively canvassed the state for Andrew Jackson, who appointed him United States district attorney for Louisiana, but after a year in office he resigned. Mr. Slidell was a candidate for the United States senate in 1834, but Charles Gayarre was chosen, tie disposed of his practice in 1835 and continued as a leader in Louisiana politics until 1842, when he was elected to congress as a state-rights Democrat, and served from 4 December, 1843, till 10 November, 1845. In November, 1845, he was sent as minister to Mexico by President Polk, to adjust the difficulty caused by the annexation of Texas to the United States: but that government refused to receive him, and he returned in January, 1847, when he resigned. He was again a candidate for the United States senate in 1849; but his party were in the minority, and in the canvass of 1852 he was active in behalf of Franklin Pierce. On the inauguration of the latter he refused a diplomatic appointment to Central America, but, on the acceptance by Pierre Soule of the French mission, he was sent to the United States senate and served, with reelection, from 5 December, 1853, to 4 February, 1861. He rarely spoke, but was a member of important committees, and exerted great influence. Preferring to remain in the senate, he declined a cabinet appointment from President Buchanan, but continued a confidential friend of the latter ministration. Mr. Slidell was a strenuous supporter of the doctrines of state-rights, and, when Louisiana passed the ordinance of secession, he withdrew from the senate with his colleague, after making a defiant speech. In September, 1861, he was appointed Confederate commissioner to France, and set out with James M. Mason for Southampton from Havana in November. He was seized on the high-seas by Captain Charles Wilkes, and brought to the United States. After imprisonment in Fort Warren he was released and sailed for England on 1 January, 1862. From England he went at once to Paris, where, in February, 1862, he paid his first visit to the French minister of foreign affairs. His mission, which had for its object the recognition of the Confederate states by the French government, was a failure, but the well-known sympathy of Napoleon III., who at that time was deeply interested in the project of a Mexican empire under Maximilian, did much to favor the Confederate cause. In order to secure French aid, he proposed a commercial convention, by which France should enjoy valuable export and import privileges for a long period, and which, if carried into effect speedily, on the basis of breaking the blockade, because of its legal inefficiency, would give France control of southern cotton, and in return furnish the Confederacy with ample supplies, including arms and munitions of war. This was not accepted, on account of the emperor's refusal to recognize the Confederate states unless the British authorities should co-operate. But the sympathy of Napoleon III. proved of great value, for by his secret influence Mr. Slidell was able to begin the negotiation of the $15,000,000 Confederate loan. Early in 1863 the emperor permitted him to make proposals for the construction of four steam corvettes and two iron-clad rams at private ship-yards in Bordeaux and Nantes ; but later in the year, information of this fact coming to the knowledge of the United States representative in Paris, imperial orders were issued that the vessels should be sold to foreign powers. One of them was transferred to the Confederate navy in January, 1865, after being purchased by Denmark, as is claimed by the Confederates, though it is asserted on the other side that the purchase was fictitious. This vessel, the " Stonewall," set out for the United States, but did not reach Havana till May, after the surrender of the Confederate armies. Mr. Slidell settled in England at the close of the war, and continued there till his death. A full account of the relations of Mr. Slidell with the French government in regard to the building of the vessels mentioned above is contained in "France and the Confederate Navy," by John Bigelow (New York, 1888).--His brother, THOMAS (1810-'60), was a judge of the Louisiana supreme court in 1845-'52, and then chief justice till 1855, when he was assaulted by a ruffian and received injuries from which he never recovered. With Judah P. Benjamin, he prepared a "Digest of Supreme Court Decisions."