Charles Vane , 3rd Marquess of Londonderry Charles William Vane , 3rd Marquess of Londonderry KG , GCB , GCH , PC ( 18 May 1778 – 6 March 1854 ) , was a British soldier , politician and nobleman . Charles Stewart ( as he was before 1822 ) was educated at Eton and was commissioned into the British army in 1794 . He saw active service in Flanders and Ireland before being elected as a member to the Irish House of Commons . In 1803 he was aide - de - camp to King George III and four years later became Under - Secretary of State for War and the Colonies . He fought in the Peninsula War under both Sir John More and Sir Arthur Wellesley ( who became the Duke of Wellington ) . In 1810 Steward was appointed Envoy Extraordinary to the Prussian Court in Berlin and remained in that position until end of the war in 1814 . In 1815 he was appointed British Ambassador to Vienna ( a post he was to hold for nine years ) , and was at the Congress of Vienna with his half brother Lord Castlereagh ( the senior British plenipotentiary ) . Charles Stewart succeeded his half - brother as 3rd Marquess of Londonderry in 1822 . The following year he was created Earl Vane and Viscount Seaham . From 1823 he was Governor of County Londonderry and was appointed Lord Lieutenant of Durham in 1842 . He was made a Knight of the Garter in 1853 , and died a year later at Londonderry House . Political career . Born in Dublin , Charles Stewart ( as he then was ) , was the only son of Robert Stewart , 1st Marquess of Londonderry , by his second wife Lady Frances , daughter of Charles Pratt , 1st Earl Camden . Robert Stewart , Viscount Castlereagh , was his half - brother . Charles Stewart was educated at Eton , and at the age of 16 was commissioned into the British Army as a Lieutenant . He saw service in Flanders in 1794 , and was Lieutenant Colonel of the 5th Royal Irish Dragoons by the time he helped put down the Irish Rebellion of 1798 . Two years later he was elected to the Irish House of Commons as Tory representative for Thomastown , County Kilkenny , and after only two months exchanged this seat for that of Londonderry County . He sat for the latter constituency until the Act of Union in 1801 , and represented then Londonderry in the British House of Commons until 1814 . ' Fighting Charlie ' . In 1803 Stewart was appointed aide - de - camp to King George III , and four years later became Under - Secretary of State for War and the Colonies . During the Corunna Campaign of 1808 – 1809 he commanded a brigade of cavalry , and played a prominent role in the cavalry clash of Benavente . In April 1809 he was made Adjutant General to Sir Arthur Wellesley ( later the Duke of Wellington ) with the British forces fighting in the Peninsular War , a post in which he distinguished himself , particularly at the battles of Busaco and Talavera . He received the thanks of Parliament in 1810 , and on 20 November 1813 was made Colonel of the 25th Light Dragoons , becoming a Knight of the Bath that same year . Until the end of the war he was Envoy Extraordinary and Minister Plenipotentiary to Berlin , and was also Military Commissioner with the allied armies , being wounded at the Battle of Kulm . The recipient of numerous foreign honours , Stewart was also , in 1814 , ennobled as Baron Stewart , of Stewart ' s Court and Ballylawn in the County of Donegal . That same year he received honorary degrees from Oxford and Cambridge , was admitted to the Privy Council , and was appointed a Lord of the Bedchamber to the King . He was also made Ambassador to Vienna , a post he held for nine years , and was at the Congress of Vienna with his half brother Lord Castlereagh as one of the British plenipotentiaries , where , according to the renowned historian Adam Zamoyski in his book " Rites of Peace : The Fall of Napoleon and the Congress of Vienna " , he made a spectacle of himself with his loutish behaviour , being apparently rather often inebriated , frequenting prostitutes quite openly , touching up young women in public , and once even starting a fist fight in the middle of the street with a Viennese coach driver ( from whom he had to be rescued by the Austrian constabulary ) . He was appointed GCH in 1816 and made colonel of the 10th ( The Prince of Wales ' s Own ) Regiment of ( Light ) Dragoons ( Hussars ) on 3 February 1820 . Marriages and family . His first wife was Lady Catherine Bligh , daughter of the 3rd Earl of Darnley , whom he married in 1804 ; she was three years older than he . She died during the night of 10 – 11 February 1812 , of fever following a minor operation , while her husband was on active service in the Peninsula . After he married his second wife Lady Frances Anne Vane - Tempest , daughter and heiress of Sir Henry Vane - Tempest , on 3 April 1819 , Lord Londonderry took the surname of Vane , by royal licence , and used his new bride ' s immense wealth to acquire the Seaham Hall estate in County Durham with a view to developing the coal fields there . He also built the harbour at Seaham , to rival nearby Sunderland . The family also used their new - found wealth to redecorate their main country seat in Ireland , Mount Stewart , and bought Holderness House on London ' s Park Lane , which they renamed Londonderry House . Charles Stewart succeeded his half - brother as 3rd Marquess of Londonderry in 1822 . The following year he was created Earl Vane and Viscount Seaham , of Seaham in the County Palatine of Durham , with remainder to the heirs male of the body of his second wife . Governor of County Londonderry from 1823 , Londonderry was appointed Lord Lieutenant of Durham in 1842 and the following year became Colonel of the 2nd Regiment of Life Guards . He was finally made a Knight of the Garter in 1853 , and died a year later at Londonderry House . Scrabo Tower in Newtownards , County Down was erected in his memory . He was succeeded as 4th Marquess of Londonderry by his son from his first marriage , and as 2nd Earl Vane by his son from his second marriage . Through his daughter Lady Frances , Lord Londonderry was the great - grandfather of Winston Churchill .