Northern Rhodesia had been detained without trial, following claims that they had planned the indiscriminate killing of Europeans and Asians, and of African opponents, the so-called "murder plot". Shortly afterwards, on 12 March 1959, the governor of Northern Rhodesia also declared a State of emergency there, arrested 45 Zambia African National Congress including Kaunda and banned the party. Kaunda later received a 19-month prison sentence for conspiracy, although no credible evidence of conspiracy was produced. The declaration of States of emergency in both Northern Rhodesia and Nyasaland marked the end of attempts by their nationalist parties to work within the colonial system,
Northern Rhodesia of further white minority governments in Africa, talk of amalgamation resumed. In 1927, the British government appointed the Hilton Young Commission on the possible closer union of the British territories in East and Central Africa. Its majority thought that Northern Rhodesia and Nyasaland should seek closer links with East Africa, but the minority report favoured linking these two territories with Southern Rhodesia on economic grounds. Even before the Commission's report was published, there were discussions between the Northern Rhodesian settlers and the Southern Rhodesian government on the terms of a total union of the two Rhodesias as a single colony.