# Dictionary of National Biography, 1885-1900/Thesiger, Frederick (d.1805)

​THESIGER, Sir FREDERICK (d. 1805), naval officer, was the eldest son of John Andrew Thesiger (d. 1783), by his wife, Miss Gibson (d. 1814) of Chester. He was the uncle of Frederick Thesiger, first baron Chelmsford [q. v.] He made several voyages in the marine service of the East India Company, but, growing tired of the monotony of trade, he entered the royal navy as a midshipman under Sir Samuel Marshall. At the beginning of 1782, when Rodney sailed for the West Indies, he was appointed acting-lieutenant on board the Formidable, and on the eve of the action with the French on 12 April, on the recommendation of Sir Charles Douglas, captain of the fleet, he was appointed aide-de-camp to Rodney. Thesiger continued in the West Indies under Admiral Hugh Pigot (1721?–1792) [q. v.], Rodney's successor, and afterwards accompanied Sir Charles Douglas to America. On the conclusion of peace in 1783 he returned to England.
In 1788, on the outbreak of war between Russia and Sweden, Thesiger obtained permission to enter the Russian service. He was warmly recommended to the Russian ambassador by Rodney, and in 1789 was appointed to the command of a 74-gun ship. He distinguished himself in the naval en​gagement of 25 Aug., obliging the Swedish admiral on board the Gustavus to strike to him. In June 1790 a desperate action was fought off the island of Bornholm. Victory declared for the Russians, but of six English captains engaged in their service Thesiger was the only survivor. In recognition of his services in this action he received from the Empress Catherine the insignia of the order of St. George. In 1796 Sir Frederick accompanied the Russian squadron which came to the Downs to co-operate with the English fleet in the blockade of the Texel.
On the death of the Empress Catherine in 1797 he grew discontented with her successor, Paul, and, notwithstanding his solicitations, persisted in tendering his resignation. He was detained in St. Petersburg a year before receiving his passport, and finally departed without receiving his arrears of pay or his prize money. He arrived in England at a time when her maritime supremacy was threatened by the northern confederacy formed to resist her rigorous limitation of the commercial privileges of neutrals and her indiscriminate application of the right of search. On account of his peculiar knowledge of the Baltic and the Russian navy Thesiger was frequently consulted by Earl Spencer, the first lord of the admiralty. When war was decided on, he was promoted to the rank of commander, and at the battle of Copenhagen served Lord Nelson as an aide-de-camp. At the crisis of the battle he volunteered to proceed to the crown prince with the flag of truce, and, knowing that celerity was important, he took his boat straight through the Danish fire, avoiding a safer but more tardy route. During the subsequent operations in the Baltic his knowledge of the coast and of the Russian language proved of great value. On his return to England bearing despatches from Sir Charles Morice Pole [q. v.] he received a flattering reception from Lord St. Vincent, and shortly after was raised to the rank of post-captain, obtaining at the same time permission to assume the rank of knighthood and to wear the order of St. George. On the rupture of the treaty of Amiens he was appointed British agent for the prisoners of war at Portsmouth. He died, unmarried, at Elson, near Portsmouth, on 26 Aug. 1805.
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