After the Battle of the Barracks, the ZNG expanded significantly with arms captured from the Yugoslav People's Army (Jugoslovenska Narodna Armija).

By the end of October 60 new brigades and independent battalions were established, and on 3 November the ZNG was renamed the Croatian Army (Hrvatska vojska).

[3] On 17 August tensions escalated into an open revolt by the Croatian Serbs,[1] centred on the predominantly Serb-populated areas of the Dalmatian hinterland near the southern town of Knin,[4] parts of the Lika, Kordun and Banovina regions and eastern Croatia.

[5] They established a Serbian National Council in July 1990 to coordinate opposition to Croatian President Franjo Tuđman's policy of pursuing independence for Croatia.

Although the operation was prepared by December 1990, federal Defence Minister General Veljko Kadijević never sought authorisation to carry it out from the Yugoslav Presidency.

Its formation as a police force with military capability was considered necessary by Croatian authorities after March clashes in Pakrac and at Plitvice Lakes and the possibility of further confrontation with the JNA.

Since it was illegal to establish a separate military in a constituent republic of Yugoslavia, the ZNG was planned as part of the police force under the Ministry of the Interior.

[9] On 18 May the Zrinski Battalion was established as a special forces unit of the ZNG, its core consisting of 27 volunteers drawn from the Kumrovec SPU.

[10] By July, the reserve force of 40,000 ZNG troops was assigned to 19 brigades and 14 independent battalions; however, they did not possess sufficient heavy or small arms for all their personnel.

Mobilisation proved particularly successful, however, and troops were plentiful; in Zagreb, approximately 80 percent of those called up in September and October reported for service.

[17] In mid-September the regional commands were replaced by six operational zones, headquartered in Osijek, Bjelovar, Zagreb, Karlovac, Rijeka and Split.

[20] On 20 September Parliament enacted the Defence Act, specifying that the ZNG and the Croatian Army (Hrvatska vojska – HV) comprised the Armed Forces of the Republic of Croatia.

[24] ZNG units participated is a number of significant battles in the early part of the war, attempting to hold back Yugoslav forces.

These include the battles of Gospić,[25] Šibenik[26] and Zadar,[27] where the ZNG defended cities in Lika and along the Dalmatian coast against the JNA and its allies.

[40] By the end of 1991, the HV still lacked sufficient resources to push back the JNA and continued experiencing inadequate work by their staff.