British India McMahon was commissioned as a
lieutenant into the
King's (Liverpool) Regiment on 10 March 1883. He transferred to the
Indian Staff Corps in 1885, joining the 1st Sikh Infantry in the
Punjab Frontier Force. In 1887, McMahon joined the Punjab Commission (civil service). He transferred to the
Indian Political Department in 1890, serving in it till 1915. His various positions included North-West Frontier, Zhob and Thal-Chotiali agencies in
Balochistan,
Gilgit,
Dir–
Swat–
Chitral and finally as the Agent to the Governor-General for Balochistan (a position that combined the Chief Commissioner for
British Baluchistan and Political Resident for the
Baluchistan Agency). McMahon spoke
Persian,
Pashto, and
Hindustani, and his aptitude for languages led him also to learn
Arabic. In 1911, the Viceroy
Lord Hardinge appointed McMahon as the Foreign Secretary to the Government of India. He held this position till 1915. During 1913–1914, McMahon was responsible for holding the tripartite conference to negotiate the
Simla Convention between Tibet, China and Britain, and acting as Britain's plenipoteniary. Though the conference failed to produce a signed convention between all three parties, Tibet and Britain did agree the draft convention, which governed their mutual relations till the end of British rule in India. Tibet and Britain also agreed their mutual border in the northeast India, which bears the name
McMahon Line.
Middle East In 1915, McMahon was sent to replace Sir
Milne Cheetham, briefly acting for
Lord Kitchener, who had become
War Secretary in London, in the post of
High Commissioner in the
Sultanate of Egypt. When he arrived by train,
Ronald Storrs, a member of the
Arab Bureau, described him as "quiet, friendly, agreeable, considerate and cautious", although later in his career Storrs and others were not so charitable. McMahon was made a
Knight of Grace of the Most Venerable Order of the Hospital of Saint John of Jerusalem (KStJ). Although a temporary appointment, it became a permanent post, for an experienced political administrator. With the approval of Kitchener and Foreign Secretary
Sir Edward Grey, McMahon began a long correspondence with
Husayn bin Ali,
Sharif of Mecca, the Ottoman-appointed ruler of the Hijaz, to use the Bedouin tribes under his control to support the
Egyptian Expeditionary Force in overthrowing the Ottomans. He promised Husayn an independent area under Arab governance that was to include what was then the
Mutasarrifate of Jerusalem (later
Mandatory Palestine), in exchange for Arab support in Britain's conflict against the
Ottoman Turks in what came to be known as the
Great Arab Revolt against the Ottomans. Their correspondence is known to historians from the
McMahon–Hussein Correspondence.
Sir Gilbert Clayton,
Aubrey Herbert, Storrs and others of the intelligence community approved of McMahon's pro-Arabist policy from 1916 onwards. McMahon sat on the plan to use the Sharif to support British for six months. But it was
Sir Reginald Wingate who persuaded McMahon that the Arabs were ready, able and willing for Cairo to support Husayn in an effort to overthrow the Ottomans and establish a pan-Arab state made up of Ottoman Arab lands in the Middle East. Storrs thought the diplomacy was "in every way exaggerated." 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
British Indian Army. By May 1916, Turkish troops had arrived in Mecca, and McMahon received a telegram from
Abdullah ibn Husayn, Sharif Husayn's son, that the Movement was ready. McMahon despatched the oriental secretary, Storrs, to London with a team of intelligence experts. The British decision to land an invasion force in the Dardanelles, instead of Alexandretta, and to promise the French Syria under the
Sykes-Picot Agreement, irritated McMahon. On 23 November 1917, following the
October Revolution, the
Bolsheviks released copies the Sykes–Picot Agreement and other secret treaties, publishing full texts in
Izvestia and
Pravda.
The Manchester Guardian then printed the texts on 26 November 1917. This caused great embarrassment to the Allies and growing distrust between them and the Arabs, and McMahon resigned his post in protest. ==Honours in retirement==