He fought during the first Shaba war in 1977 and second Shaba war in 1978, when ex-Katangese gendarmes invaded the Shaba province (formerly Katanga) from Angola and Zambia and were pushed back by the FAZ and international interventions. During Shaba II's Battle of Kolwezi, thirty European residents were murdered in a villa in the P2 quarter of the city during the so-called "P2 massacre" in May 1978. Blamed by Zaire's President Mobutu Sese Seko on the rebels, Yambuya nevertheless claimed that FAZ Colonel Bosange ordered his troops to shoot through the blinds of the villa, killing the Europeans who sought refuge. One rumour even claimed that they were murdered by FAZ forces to provoke a foreign intervention. The international decision to intervene, however, was already taken by that time.