 Skirmishes began between UNAR and PARMEHUTU groups.In July 1959, when the Tutsi Mwami (King) Mutara III Charles died following a routine vaccination, some Tutsi thought he had been assassinated.His younger half-brother became the next Tutsi monarch, Mwami (King) Kigeli V.

In November 1959, Tutsis tried to assassinate Kayibanda.