of the commission and establishing the 'Danube Rule' of measurement, which was a modification of the English rule.
On 6 July 1867 Stokes was promoted to be a regimental lieutenant-colonel and paid one of his periodical visits home. He prevailed on Lord Stanley, then foreign secretary, to provide needful financial help for the moment and to arrange with the powers concerned to guarantee a loan, which was sanctioned next year by an international convention, Russia alone standing out. Great Britain gave effect to the convention in the 'Danube Loan Act.' When in the autumn of 1870 Russia repudiated the Black Sea articles of the treaty of Paris, Stokes urged the British government to secure in perpetuity European control over the mouths of the Danube by means of the commission. During the congress in London in 1871 he acted as the intermediary of Lord Granville, foreign secretary, with the foreign ambassadors and plenipotentiaries on questions affecting the Danube. He arranged the terms with them and drafted the articles on the Danube in the treaty of London of March 1871. For his services he was created a C.B., civil division.
The works at the Sulina branch of the Danube were now approaching completion ; the channel had been increased from eight or nine to twenty feet at low water, and was available for large ships for a hundred miles above its mouth ; the new tariff gave a yearly increasing income for the maintenance of the navigation, the river was well lighted, and the pilotage satisfactorily arranged (see Stokes's paper on the mouths of the Danube in Roy. Eng, Establishment Papers, 1865, and 'The Danube and its Trade' in Soc. of Arts Journal, 1890). Accordingly, when the war office summoned Stokes to return to corps duties, if he wished to remain on the effective list, he resigned the commissionership. In 1872 he was appointed commanding royal engineer of the South Wales military district, and on 4 June 1873 received a brevet colonelcy.
But international diplomacy continued to be his main occupation. Stokes served at Constantinople as British commissioner (Oct.-Dec. 1873) on the international commission to settle a difficulty that had arisen over the Suez Canal dues, which, hitherto calculated by the canal company on net tonnage, had recently been charged on gross tonnage. The view of the majority of the commissioners in favour of the charge on net tonnage was resisted on behalf of the canal company by the representatives of France and some other powers. The difference was settled by a compromise, which Stokes proposed, to the effect that in addition to the ten francs a ton on net tonnage, the company should be empowered to levy a surtax of three and a half francs a ton, to be reduced in certain defined proportions as the traffic through the canal increased. The sultan marked his satisfaction by promoting Stokes to the second class of the order of the Mejidie in 1874. After reporting for the foreign office on the condition of the canal, Stokes in the spring resumed his duties at Pembroke Dock. M. Ferdinand de Lesseps, however, objected to the arrangements made at Constantinople, and Stokes was in frequent attendance at the foreign office. Early in 1875 he was made commanding royal engineer of the Chatham district, to be more within reach.
On 1 Nov. 1875 he was appointed commandant of the School of Military Engineering at Chatham. Later in the month his opinion was invited as to the purchase, which he advised, of the Khedive's shares in the Suez Canal, and subsequently at the Khedive's request the British government sent Mr. Cave of the paymaster-general's department and Colonel Stokes to Egypt for four months to examine and report on the Khedive's financial embarrassments. In pursuit of separate instructions he concluded a convention settling outstanding difficulties with M. de Lesseps and the Suez Canal Company under the Constantinople agreement of 1873. The terms included representation of the British government on the board of directors, and Stokes was nominated to the board in June 1876. Next year he was created a K.C.B., civil division. During 1879-80 he served on an international commission, with headquarters at Paris, to examine the works at the port of Alexandria in Egypt, and decide what dues should be levied on the shipping. la Nov. 1880 he joined the royal commission on tonnage measurement, which reported in 1881. Appointed deputy adjutant-general for royal engineers at the war office on 1 April 1881, Stokes was a member of the Channel tunnel committee, and opposed its construction in 1882. The Egyptian expedition of that year exposed him to some friction with French colleagues on the Suez Canal board, who object to the use made of the canal by the British authorities, but his tact overcame all objections, and he received the personal thanks of Gladstone, the prime minister, for his good service. In March 1885 Stokes
