Flag of Zanzibar yellow cloves was added to the flag. On 12 January 1964, John Okello overthrew the Sultan of Zanzibar and adopted a black-yellow-blue tricolour as the flag of the People's Republic of Zanzibar and Pemba. On 29 January, the country's flag was changed to a blue-black-green tricolour with a thin white stripe at the hoist. This design, which was based on the flag of the Afro-Shirazi Party, was the longest-lived of the post-independence flags and eventually formed the basis for the current flag. On 26 April 1964, Zanzibar united with Tanganyika to form the new country of Tanzania and Zanzibar's old
People's Republic of Zanzibar US citizens on the island, and a US Navy destroyer, the USS "Manley", arrived on 13 January. The "Manley" docked at Zanzibar Town harbour, but the US had not sought the Revolutionary Council's permission for the evacuation, and the ship was met by a group of armed men. Permission was eventually granted on 15 January, but the British considered this confrontation to be the cause of much subsequent ill will against the Western powers in Zanzibar. Western intelligence agencies believed that the revolution had been organised by communists supplied with weapons by the Warsaw Pact countries. This suspicion was strengthened