Although Carnarvon's attempt to unite South Africa in the 1870s was a failure, the forward movement represented by his “confederation policy” marks an important turning point in South African history. The destruction of the Zulu and the Pedi polities, which resulted directly from the confederation scheme, together with the last Cape frontier war and a rash of smaller conflicts, constituted the virtual end of organized black resistance in the nineteenth century and the beginning of untrammelled white supremacy. Britain's annexation of the Transvaal in 1877, which Carnarvon had hoped would be the decisive move towards confederation, instead set the scene for the conflict between Boer and Briton which dominated the history of the last two decades of the nineteenth century in South Africa.
Carnarvon's confederation scheme had important effects, but there is little agreement on its causes. The author of the standard work on the subject, Clement Goodfellow, took the view that Carnarvon's interest in South Africa arose essentially from its strategic importance within the empire as a whole. The Cape lay athwart the vital sea-route to Britain's eastern possessions, and confederation was designed, in Goodfellow's words, “to erect from the chaos of the subcontinent a strong, self-governing, and above all loyal Dominion behind the essential bastion at Simon's Bay.” This view, or some variant of it, sometimes with “Simonstown” or “Cape Town” or “the naval bases” or “the Cape peninsula” substituted for “Simon's Bay,” has been widely accepted and now appears as a matter of fact in the most recent and widely used general accounts of South African history.