The son of Chief Jean-Berchmans Manzi, he was a member of the Banyiginya clan and the Bakobwa lineage[1] and was ethnically Tutsi.
[1] He became a vice president of the Rwandese National Union (UNAR), an anticolonial political party, after its formation in 1959[1][3] and served as a leader of its progressive faction.
[4] In October, Governor Jean-Paul Harroy of Ruanda-Urundi attempted to transfer Kayihura from his chiefdom to head off political disorder.
[1] The UNAR restorationists formed a government-in-exile shortly before Rwanda's independence, with François Rukeba as Prime Minister.
Kayihura founded a rebel group, the Rwandese Liberation Front, and spent most of his time traveling between Geneva and Brussels to win foreign support for it.