The Uganda Army invaded Tanzania in late 1978, resulting in the Uganda–Tanzania War's outbreak. Oyite-Ojok assumed a key role in the grouping of military exiles who, with the backing of Tanzanian troops, led the counteroffensive which resulted in the overthrow of Amin. At first, he served as field commander for Obote's private army Kikosi Maalum, and was appointed head of a Uganda National Liberation Army (UNLA) battalion in March 1979. With the latter unit, he fought alongside the Tanzanians in central and eastern Uganda. Oyite-Ojok proved to be tactically adept during this conflict. He eventually rose to chief of staff for the entire UNLA.