On 28 August 1985, the Zimbabwean and Mozambican government troops attacked the headquarters of the Mozambican National Resistance (Renamo) located at Casa Banana. Casa Banana is situated to the east of Gorongosa Mountains, at the far north of the Gorongosa National Park, about 22 km east of Vinduzi, to the north of the Nhadué River. Renamo expected the attack and forewarned its local groups so that they would not be affected. It withdrew its forces from the base, leaving part of the heavier armament that it had seized from the government. Despite the statement given by Samora Machel, president of the People's Republic of Mozambique and of the party in power, the Mozambique Liberation Front (Frelimo), saying: ‘We've broken the backbone of the snake’, this was not an important military victory. A foreign journalist based in Mozambique, very supportive of Frelimo, rightly commented: ‘the problem is that the snake doesn't have a backbone’. Renamo continued to operate after the loss of Casa Banana and a few months later even re-conquered its central base.

Renamo left behind heavy armament at Casa Banana as well as part of its archive, which the security services of the Mozambican government hurried to analyse and use against the guerrilla. Some of the documents were soon published to prove that Pretoria still supported Renamo, if clandestinely, with arms or other items, only months after the signature on 16 March 1984 of a Non-aggression and Good Neighbourhood Agreement, commonly called the Nkomati Accord, which set forth that the Mozambican government would no longer support the African National Congress in exchange for the South African government ending its support of Renamo.

The Mozambican government published excerpts of the ‘Cadernos de Gorongosa’ (‘Gorongosa Notebooks’), i.e. fragments of Renamo's archives where the presence of South Africa in the rebel group's life could be undoubtedly ascertained. There were two consecutive editions of the Notebook entitled Documentos de Gorongosa (‘Gorongosa Documents’). The second edition was larger and bilingual, with a new section entitled ‘1984: Diary/Desk Diary’ which created a third section after ‘Notebook 2’ and ‘Notebook 3’. Afonso Dhlakama, Commander-in-Chief of Renamo's forces at the time, immediately declared that the documents published were fakes, forged by SNASP.