Henry McMahon ( diplomat ) Lieutenant Colonel Sir Arthur Henry McMahon , GCMG , GCVO , KCIE , CSI , KStJ ( 28 November 1862 Simla , British India — 29 December 1949 London , United Kingdom ) , was a British diplomat and Indian Army officer who served as the High Commissioner in Egypt from 1915 to 1917 . He was also an administrator in British India , and served twice as Chief Commissioner of Balochistan . McMahon is best known for the McMahon - Hussein Correspondence , as well as the McMahon Line between Tibet and India . He also features prominently in T . E . Lawrence ' s account of his role in the Arab Revolt against the Ottoman Empire during World War I , Seven Pillars of Wisdom . He is usually known as Sir Henry McMahon . Background . McMahon was the son of Lieutenant - General Charles Alexander McMahon , FRS , FGS ( 1830 – 1904 ) , a geologist and Commissioner of both Lahore and Hisar in British India , and who , like his father Captain Alexander McMahon ( born 1791 in Kilrea , County Londonderry , Ireland ) had been an officer with the East India Company . The McMahon s are the Gaelic clan of Mac Mathghamhna who had come originally from the medieval Irish kingdom of Airgíalla or Oriel in South Ulster / North Leinster , where they reigned from around 1250 until about 1600 . Sir Henry McMahon ' s own family had settled in the Downpatrick area of County Down before his great - grandfather , The Rev . Arthur McMahon , moved to Kilrea , where he was minister to the local Presbyterian congregation between 1789 and 1794 : a prominent Irish Republican , The Rev . McMahon was a member of the National Directory of the Society of United Irishmen and one of their colonel s in Ulster during the Irish Rebellion of 1798 . He apparently fought at the battles of Saintfield and Ballynahinch and after the rebels ' overall defeat had been able to flee to France where he served with Napoléon ' s Irish Legion . It is said that he was captured by the British during the Walcheren Campaign of 1809 , and though sent to England , was later able to return to France where in June 1815 he eventually died fighting , it is believed , at either Ligny or of Waterloo . Career . McMahon was commissioned a Lieutenant in the Indian Staff Corps in the 1880s and was appointed a Companion of the Most Eminent Order of the Indian Empire ( CIE ) in 1894 . By 1897 , he had been promoted to captain and was appointed a Companion of the Most Exalted Order of the Star of India ( CSI ) in that year . He was promoted Major in the army in July 1901 . He was knighted as a Knight Commander of the Most Eminent Order of the Indian Empire ( KCIE ) in 1906 and promoted to the rank of Lieutenant Colonel in 1909 . In 1911 , on the occasion of the Delhi Durbar , he was appointed a Knight Grand Cross of the Royal Victorian Order ( GCVO ) and was appointed to the post of High Commissioner in Egypt in 1914 . In 1915 , he was made a Knight of Grace of the Most Venerable Order of the Hospital of Saint John of Jerusalem ( KStJ ) . He was appointed a Knight Grand Cross of the Most Distinguished Order of Saint Michael and Saint George ( GCMG ) in 1916 upon his retirement from the Indian Army . In 1920 , he was awarded the Order of El Nahda , 1st Class , from the King of the Hejaz . In 1925 , he was promoted to a Knight of Justice of the Most Venerable Order of the Hospital of Saint John of Jerusalem ( KStJ ) .