1st Army Group (Kingdom of Yugoslavia)

1st Army Group
Country	Yugoslavia
Branch	Royal Yugoslav Army
Type	Infantry
Size	Field army[a]
Engagements	Invasion of Yugoslavia (1941)
Commanders
Notable commanders	Milorad Petrović

The 1st Army Group was a Royal Yugoslav Army formation mobilised prior to the German-led Axis invasion of Yugoslavia in April 1941 during World War II. It consisted of the 4th Army, 7th Army, and the 1st Cavalry Division, which was the army group reserve. It was responsible for the defence of northwestern Yugoslavia, with the 4th Army defending the eastern sector along the Yugoslav–Hungarian border, and the 7th Army defending the western sector along the borders with Germany and Italy. Like all Yugoslav formations at the time, the 1st Army Group had serious deficiencies in both mobility and firepower as well as internal friction among the different ethnic groups, particularly between Serbs and Croats.

Despite concerns over a possible Axis invasion, orders for the general mobilisation of the Royal Yugoslav Army were not issued by the government until 3 April 1941, not to provoke Germany any further and precipitate war. When the invasion commenced on 6 April, the component formations of 1st Army Group were only partially mobilised, and on the first day the Germans seized bridges over the Drava River in both sectors and several mountain passes in the 7th Army sector. In the 4th Army sector, the formation and expansion of German bridgeheads across the Drava were facilitated by fifth column elements of the Croat fascist and ultranationalist Ustaše. Mutiny by Croat soldiers broke out in all three divisions of the 4th Army in the first few days, causing significant disruption to mobilisation and deployment. The 1st Army Group was also weakened by fifth column activities within its major units when the chief of staff and chief of operations of the headquarters of 1st Army Group aided both Ustaše and Slovene separatists in the 4th and 7th Army sectors respectively. The revolts within the 4th Army were of great concern to the commander of the 7th Army, Diviziski đeneral Dušan Trifunović, but the army group commander, Armijski đeneral Milorad Petrović, did not permit him to withdraw from border areas until the night of 7/8 April, which was followed by the German capture of Maribor as they continued to expand their bridgeheads.

The 4th Army also began to withdraw southwards on 9 April, and on 10 April it quickly ceased to exist as an operational formation in the face of two determined armoured thrusts by the XXXXVI Motorised Corps, one of which captured Zagreb that evening where a newly formed Croatian government hailed the entry of the Germans. Italian offensive operations also began, with thrusts towards Ljubljana and down the Adriatic coast, capturing over 30,000 Yugoslav troops near Delnice. When fifth column elements arrested the staffs of the 1st Army Group, 4th Army and 7th Army on 11 April, the 1st Army Group effectively ceased to exist. On 12 April, a German armoured column linked up with the Italians near the Adriatic coast, encircling the remnants of the withdrawing 7th Army. Remnants of the 4th Army attempted to establish defensive positions in northeastern Bosnia, but were quickly brushed aside by German armour as it drove towards Sarajevo. The Yugoslav Supreme Command unconditionally surrendered on 18 April.
Cite error: There are <ref group=lower-alpha> tags or {{efn}} templates on this page, but the references will not show without a {{reflist|group=lower-alpha}} template or {{notelist}} template (see the help page).