In December, 1870, the difficulties between England and the United States, which had held over until then from the Civil War, were satisfactorily settled by international commissioners at Geneva. A revolution of French-Canadians broke out in 1872, but was quickly put down. Cape Colony added to its territory in 1871 by annexing, over the protests of the Orange Free State, territory known then as Griqualand West. In the same year the Gold Coast was acquired on the West Coast of Africa through a treaty with Holland, Great Britain relinquishing in exchange its claims to Dutch Indian Sumatra. Russia's increased activity in Asia caused considerable apprehension, which, however, was removed by an understanding between Russia and Great Britain, concluded in 1872, according to which Afghanistan was to be considered not within the sphere of Russian interests in Asia. In 1874 the ties of relationship which connected Queen Victoria's family to that of the czar were strengthened by the marriage of her son, the Duke of Edinburgh, to Grand Duchess Marie of Russia. In the same year Czar Alexander II visited London. The Gladstone Ministry was succeeded by one headed by Disraeli. In 1875 the Government announced the purchase of the Suez Canal shares, then held by the Khedive of Egypt. This practically gave England control of the canal, as the khedive's holdings amounted to nine-twentieths of the entire issue. A great many of the other shares were in the hands of French investors. But the French Government accepted England's purchase without opposition. This move not only secured to England control of the shortest and safest route to India, but also brought it into closer contact with Egypt, one of the great colonial prizes of the world then still available. Disraeli soon gave proof of the sincerity of his imperialistic views. In 1876, at his suggestion and as a result of his diplomacy, the queen was proclaimed Empress of India. In 1877 the Transvaal was annexed by England. In the Russo-Turkish War, which broke out that year, England maintained neutrality, but in 1878 a defensive treaty was signed between Great Britain and Turkey which gave the island of Cyprus to England. In 1879 the Zulu War broke out and kept English forces engaged through the greater part of the year. The following year, 1880, was marked chiefly by riots and bloodshed in Ireland, the resignation of Disraeli, and the return to the premiership of Gladstone, who in 1881 succeeded in passing the Irish Land Bill. The Irish difficulties lasted throughout 1882, 1883, and 1884. Throughout that year, 1884 and 1885, English troops fought rebellious natives in Egypt after having announced to Turkey that it felt that it was necessary for the protection of the Suez Canal that British troops should assume the responsibility of restoring order in Egypt.