helped to expedite the fatal enterprise, and
at the end of the disastrous campaign he
was promoted to a brevet colonelcy (15 June
1885), receiving the third class of the order
of the Medjidieh. On 30 Dec., as chief staff
officer of a combined British and Egyptian
force, he took part in the engagement at
Giniss, when a large army of the Khalifa,
which was endeavouring to invade Egyptian
territory, after the abandonment of the
Soudan, was defeated with great loss. For
his services Ardagh was mentioned in
despatches. On 17 Dec. 1886 he was
promoted to a regimental lieutenant-colonelcy, and on 26 Jan. 1887 he was gazetted a colonel on the staff.
In Nov. 1887 Ardagh returned to London
as assistant adjutant-general for defence
and mobilisation at the war office, and he
inaugurated schemes of mobilisation for
over-sea service, and of local home defence.
From April 1888 to 1893 he was aide-de-camp to the duke of Cambridge, commander-in-chief. In October 1888 he became, with war office sanction, private secretary to the marquis of Lansdowne, viceroy of India. Save for a period of absence through illness in 1892, he remained with Lord Lansdowne through his term of office. He returned to England in May 1894, after a short service with Lord Lansdowne' s successor, Lord Elgin. He was made a C.I.E. in 1892, and K.C.I.E. in 1894.
Ardagh had spent less than a year as commandant of the School of Military Engineering at Chatham (from 16 April 1895), when he rejoined (27 March 1896) the war office for five years as director of military intelligence, with the temporary rank of major-general. He was promoted major-general on the establishment, on 14 March 1898. The South African war broke out in October 1899, and during the black days at the opening of the campaign an outcry was made that Ardagh's department had not kept the government informed of the number of men the Boers could put into the field, nor of the preparations they had made for the war. Yet Ardagh, in spite of a limited staff and inadequate funds, had performed his duty thoroughly. He compiled for the government a full statement of the number and military resources of the Boer forces, estimating that the defence of the British colonies alone would require 40,000 men, while to carry the war into the enemy's country would require 200,000. Copies of this paper were eventually laid on the tables of both houses of parliament at Ardagh's request. Meanwhile 'Military Notes on the Dutch Republic,' a secret work prepared under Ardagh's auspices in the intelligence branch, fell early in the campaign into the hands of the Boers after the action of Talana (20 Oct. 1899), and was published. These documents, which were corroborated by evidence before the royal commission on the war, relieved Ardagh of all blame.
In addition to his ordinary duties Sir John was a member of a committee on submarine telegraph cables, and in 1899 military technical adviser to the British delegates, Sir Julian (afterwards Lord) Pauncefote [q. v. Suppl. II] and Sir Henry Howard, at the first Hague peace conference. There he took a leading part in drawing up the ' Rules respecting the Laws and Customs of War on Land.' In he was awarded the distinguished service pension.
After leaving the war office in March he showed to advantage his tact and knowledge of international law as British agent before a commission to investigate the claims of foreign powers on account of the deportation to Europe of subjects of theirs domiciled in South Africa during the war. From December 1901 to June 1902 he was in South Africa settling miscellaneous claims in connection with the war, which was still going on. He returned to South Africa later in the year with the temporary rank of lieutenant-general as member of the royal commission for the revision of martial law sentences. In October he was a member of the British tribunal on the Chili-Argentina boundary arbitration and helped to draft the award. On 9 Aug. 1902, when sixty-two years of age, Ardagh retired from military service, but was still employed by the foreign office. He succeeded Lord Pauncefote on the permanent court of arbitration at the Hague, and became a British government director of the Suez Canal. In December 1902 he was created K.C.M.G.
Ardagh was deeply interested in the British Red Cross Society, of which he became a member of council in 1905. He represented the British army, being one of four delegates of the British government in June 1906, at the conference held by the Swiss government for the revision of the Geneva Convention of 1864. The new convention was signed in the following month. His last public duty was to act as a delegate of the central committee of the society at the eighth international conference in London
