 Born in Gorongosa, Mozambique, Matsangaissa joined FRELIMO in 1972, and after FRELIMO's victory in 1975 he became a quartermaster stationed at Dondo, near Beira.He was punished for theft by being expelled from the Mozambican Army ("Forças Armadas de Moçambique", FAM) and was placed in a re-education camp at Gorongosa.He was freed during an attack on the camp by Rhodesian forces and was taken to Rhodesia.