In 1971 Colonel Idi Amin launched a military coup that overthrew the President of Uganda, Milton Obote, precipitating a deterioration of relations with the neighbouring state of Tanzania.

Ugandan troops subsequently pillaged the area they occupied, murdering civilians, stealing cattle, and destroying property, triggering the flight of 40,000 inhabitants southward.

[3] In November the Tanzania People's Defence Force (TPDF) launched a counterattack, retaking the salient, while the Ugandans withdrew to the border.

[4] Tanzanian commanders nevertheless felt that as long as Ugandan troops controlled the high ground at Mutukula along the frontier they posed a threat to the salient.

[5] In late December, the TPDF began launching heavy rocket attacks against Ugandan positions along the border, continuing into the next month.

[6] On the night of 21 January 1979 several battalions of the 208th Brigade crossed the Ugandan border and covertly assumed positions north and west of Mutukula.

Rwehururu attempted to telephone the Uganda Army Chief of Staff, Major General Yusuf Gowon, but was unable to reach him.

[10] At dawn, a TPDF battalion commanded by Lieutenant Colonel Salim Hassan Boma and equipped with tanks advanced down the main road from Tanzania towards Mutukula in an attempt to draw the Ugandans' attention.

The Ugandan troops concentrated their fire on Boma's battalion,[5] including bombarding them with artillery stationed to the rear of Kikanda Hill further north.

[9][c] According to Rwehururu, at around 16:00 on 22 January, a helicopter carrying Brigadier Taban Lupayi and Lieutenant Colonel Godwin Sule touched down in Sanje.

The two Ugandan commanders informed Rwehururu that the reinforcements Amin had promised him were coming from Lukaya, 120 kilometres (75 mi) north of Mutukula.

After Amin failed to renounce his claims to Kagera and the Organisation of African Unity offered only limited criticism of the Ugandan invasion, he decided that Tanzanian forces should occupy southern Uganda.

[23] Nyerere originally planned to halt his forces in Masaka and Mbarara and allow the Ugandan rebels to attack Kampala and overthrow Amin, as he feared that scenes of Tanzanian troops occupying the city would reflect poorly on his country's image abroad.

However, Ugandan rebel forces did not have the strength to defeat the Libyan units coming to Amin's aid, so Nyerere decided to use the TPDF to take Kampala.