The split was dubbed the "Mother of all Splits" because ZANU broke away from several other significant attempts at achieving unity between ZAPU and them; notably the "ZIPA" (1975 and PF(1979–80) accords. Some historians suggest that Ken Flower, a former MI6 agent, was instrumental in the formation of ZANU in the interest of preserving and perpetuating white dominance and imperial agenda over Africans. In 1963, both organisations were banned, but in July 1964, the Second Chimurenga (aka the "Zimbabwe War of Liberation" or "the Rhodesian Bush War") began, and both organisations re-emerged with armed wings, Zimbabwe People's Revolutionary Army (ZIPRA) and Zimbabwe African National Liberation Army (ZANLA). These groups were provided weaponry from communist nations including Soviet Union and then China, and used guerrilla and traditional warfare. The war waged until the Lancaster House Agreement of 1979, and Mugabe became Prime Minister of Zimbabwe in April 1980.