His election to the Cape Parliament in 1881 as Member for Kimberley placed him in a favourable position to advance his schemes for the northward extension of the British Empire.  When the trespasses and encroachments of the Transvaal Boers beyond the limits assigned to them under the Convention of 1884 made it advisable to incorporate Bechuanaland he was unable to persuade the Cape Government to undertake that responsibility, but with the assistance of Sir Hercules Robinson and the support of Mr. Chamberlain he induced the Imperial Government to take action.  President Kruger had connived at the establishment on native territory under British protection of two little republics of raiders, to which the names of Goshen and Stellaland were assigned; and a costly expedition under Sir C. Warren was needed to bring him to his senses.  In 1885 Bechuanaland became an integral part of the British Empire.

In 1888 he again opened the flood gates of Imperialism, and secured by means of a treaty with Lobengula the reversion of the native territory north of the Transvaal, at which two European nations were nibbling, and which in his honour received the name of Rhodesia.

He became Premier of the Cape Colony in 1890 by the help of the Dutch vote and from that time gradually sank from the zenith of his success.  His good fortune left him when he attained his ambition.  The Jameson Raid, for which he was not personally, though he confessed himself morally, responsible, ended his political career.  His last good service to the Empire was given during the Matabele rising.  He accompanied the troops sent to suppress the rebellion; and when the operations seemed likely to be indefinitely prolonged, he brought it to an end by going fearlessly and almost unattended among the natives, whose confidence he won by meeting them trustfully in council and listening to their grievances.

His physical vitality, always inadequate, was seriously impaired by the strain of the siege.  He never fully recovered his strength and he died on March 26, 1902, two months before the Second Boer war was brought to a close by the Vereeniging Treaty.

He was a rich but honest man, and the great wealth which he amassed never led him to attach undue importance to the possession of it.  He valued it not for his own advantage, but for its help in advancing his political and imperial schemes.  He employed it creditably and without ostentation, and spent none of it in social display in London.  By his will he left the greater portion of it to the University of Oxford for the establishment of an amiable if somewhat quixotic system of bringing the various branches of the Anglo-Saxon race into association at a centre of learning and athletics, where they were to be leavened by a Teutonic admixture.

The vision of posthumous reputation allured him, and he delighted in the hope that the name of his own Rhodesia, like the cities which still bear the name of Alexander, would be on the lips of men of generations as far distant from his own as his own was from the days of the Great Macedonian.