Danger of the Cape being cut off from the north was, however, still extant in Bechuanaland, where the Boers had annexed the territories known as Stellaland, Goshen, and Rooigrond; but this was eventually saved to Great Britain by vigorous individual action on the part of Cecil Rhodes, who had himself appointed a Commissioner to visit Bechuanaland, where he strenuously opposed the claims of the Transvaal Republic. These claims were, however, only withdrawn in the following year after an expedition under Sir Charles Warren had proceeded to the disputed areas and persuaded the Boers that Great Britain was this time in real and eager earnest. Bechuanaland became a British "Protectorate," and the well-laid scheme for a German transcontinental Empire was frustrated. The boundaries of the territory brought under German sway in South West Africa were defined by what is known as the Caprivi Treaty of the 1st July, 1890, between Germany and Great Britain, and by an agreement between Germany and Portugal. Under the terms of the latter the northern boundary of German South West Africa, between that Colony and Portuguese Angola, was fixed at the Cunene River; while under the Caprivi Treaty the boundary between the Cape Colony and German South West Africa was declared to be the Orange River. Great Britain retained Walfisch Bay, which became a "district" of the Cape Colony and was placed under the Colonial administration in 1884, and also kept the territory round Lake 'Ngami in northern Bechuanaland. The lake district was neglected, however, until Cecil Rhodes, fearing the loss of more territory unless it was beneficially occupied, sent, at his own expense, an expedition of Boer trekkers to settle on the land. Article III of the Caprivi Treaty was an important one, for thereunder it was provided that Germany should "have free access from her Protectorate (South West Africa) to the Zambezi River by a strip which shall at no point be less than twenty English miles in width." The acquisition by Germany of South West Africa was of great strategical importance, enabling them to establish in time a system of communication by wireless telegraphy which covered the whole continent. In Togoland on the west coast the most powerful wireless apparatus in the world was installed, and this was in touch both by wireless and cable with Berlin. The Togoland station was also in touch with the wireless installation at Windhoek, the capital of German South West Africa, and with Dar-es-Salaam, the German port on the east coast opposite Zanzibar.