During the fighting on 8 April, the Bosnian Croat TO was reorganised as the Croatian Defence Council (Hrvatsko vijeće obrane – HVO).

In Kupres itself, the Bosnian Croat TO achieved minor territorial gains on 4–5 April, before the JNA managed to advance to the outskirts of the town the next day.

The next year, Croatian authorities charged 21 former JNA members with war crimes against HVO prisoners captured at the Kupres Plateau.

On 27 March,[2] Bosnian Serb forces bombarded Bosanski Brod with artillery, drawing a border crossing by the Croatian Army (Hrvatska vojska – HV) 108th Brigade in response.

The bulk of the force moved to Knin three months later, while a tactical group of the 30th Partisan Division redeployed to the general area as it withdrew from Slovenia after the Ten-Day War.

In September, the Bosnian Croats established the Territorial Defence Force (Teritorijalna obrana – TO) headquarters which set up armed volunteer units.

[6] In early 1992, the 30th Partisan Division was subordinated to the JNA 5th (Banja Luka) Corps and assigned Kupres as its area of responsibility (AOR).

[7][8] In April, the Bosnian Serbs were able to deploy 200,000 troops, hundreds of tanks, armoured personnel carriers (APCs) and artillery pieces.

[10] In response, the division was tasked to deploy its elements to Kupres, Ključ, Mrkonjić Grad, Šipovo, Jajce and the Mount Vlašić, take command of the Bosnian Serb TO and repel the expected Croatian attack.

[12] The next day, the divisional commander toured the plateau and was informed that the Bosnian Croat forces were in control of the villages of Olovo, Osmanlije and Zlosela, in addition to Kupreška Vrata.

[13] At this time, both sides had a relatively small portion of their force inside Kupres, while the Bosnian Croat TO held the area adjacently surrounding the town.

[15] On 27 March, an attempt to reach a negotiated settlement failed and the commanding officer of the 19th Partisan Brigade announced that armed combat might start at a moment's notice.

[17] Kupres had a high strategic value, because it sat astride a road linking the towns of Bugojno and Tomislavgrad from the central Bosnia region to western Herzegovina and further on to Croatia.

The purpose of the meeting, attended by members of Presidency of Bosnia and Herzegovina, Biljana Plavšić and Franjo Boras, was to defuse the situation.

While there was an agreement to establish an ethnically balanced police force in Kupres and remove the roadblocks, the opposing sides could not agree on the role of the JNA.

[23] During that same day, the 30th Partisan Division ordered the forces under its command, as well as the recent reinforcements, to capture Kupres and Kupreška Vrata and then hold their ground against anticipated Croatian counterattacks.

There were also Croatian Defence Forces (Hrvatske obrambene snage – HOS) units raised in Tomislavgrad and Posušje, which were involved in the fighting around Kupres.

[29] According to the JNA, the Bosnian Croat TO attacked in the morning of 3 April, reached the village of Donji Malovan and blockaded the Kupreška Vrata Tunnel by 7:30 a.m.

[26] The JNA instructed the Yugoslav Air Force to attack after it received reports that 15 HV tanks had appeared on the battlefield.

[30] Following news of the fighting, the 5th (Banja Luka) Corps called on its troops deployed in western Slavonia to reinforce the 30th Partisan Division.

The corps felt it could weaken its positions in western Slavonia because the United Nations Protection Force (UNPROFOR) peacekeepers were expected to deploy there by the end of the month based on the Vance plan.

In the town of Kupres itself, the Bosnian Croat TO was reinforced by the arrival of a group drawn from the HV special forces Zrinski Battalion.

The most effective part of the advance was the 9th Tank Company, which quickly pushed through the defensive positions, bypassed Zlosela and reached Olovo.

[37][41] By the end of the day, the divisional reserve was committed to the battle, and the JNA claimed that they had captured Zlosela, Olovo and Osmanlije, as well as reaching the outskirts of Kupres.

The Bosnian Croat TO captured the centre of Kupres and brought the 1st Battalion of the 19th Partisan Brigade into a difficult position, only to begin withdrawing towards Tomislavgrad after the main JNA force reached the town in the night of 6/7 April.

Soon after the Battle of Kupres, a portion of the 9th Armoured Battalion was transferred to Glamoč to support the Bosnian Serb TO attack towards Livno there.