Like all Yugoslav infantry divisions of the time, it was a very large and unwieldy formation which was almost entirely reliant on animal transport for mobility, and also lacked modern arms and sufficient ammunition.

Commanded by Divizijski đeneral Borisav Ristić, it was largely manned by Croat troops, many of whom saw the Germans as potential liberators from Serbian oppression.

It was formed around the nucleus of the victorious Royal Serbian Army, as well as armed formations raised in regions formerly controlled by Austria-Hungary.

The army budget remained tight, and as tensions rose across Europe during the 1930s, it became difficult to secure weapons and munitions from other countries.

[3] Consequently, at the time World War II broke out in September 1939, the VKJ had several serious weaknesses, which included reliance on draught animals for transport, and the large size of its formations.

[7][8] The weaknesses of the VKJ in strategy, structure, equipment, mobility and supply were exacerbated by serious ethnic disunity within Yugoslavia, resulting from two decades of Serb hegemony and the attendant lack of political legitimacy achieved by the central government.

The 42nd ID was to establish positions between the triple border with Germany and Hungary and the confluence of the Mura and Drava at Legrad, with divisional headquarters at Seketin, just south of Varaždin.

[27] Similar operations occurred on the extreme left flank of the 4th Army, where raiding parties and patrols from LI Infantry Corps, commanded by General der Infanterie[d] Hans-Wolfgang Reinhard, seized high ground on the south side of the Drava.

[29] A bicycle-mounted detachment of Generalmajor[e] Benignus Dippold's 183rd Infantry Division captured Murska Sobota in the Prekmurje region without encountering resistance.

These local attacks were sufficient to inflame dissent within the largely Croat 4th Army, many of whom refused to resist Germans they considered their liberators from Serbian oppression during the interwar period.

[30] In the afternoon, German Junkers Ju 87 Stuka dive bombers of Sturzkampfgeschwader 77 escorted by Messerschmitt Bf 109E fighters caught the air reconnaissance assets of the 4th Army on the ground at Velika Gorica, destroying most of them.

During the day, Yugoslav sabotage units attempted to destroy bridges over the Mura at Mursko Središće, Letenye and Kotoriba.

[32] Reconnaissance units of the XXXXVI Motorised Corps crossed the Mura at Letenye and Mursko Središće early on 7 April, and captured Čakovec.

[33][36] The 2nd Battalion of the 36th Infantry Regiment was unable to reach its starting position for the counterattack on the Zákány bridgehead, and during the night of 7/8 April, it began to disintegrate.

[39] Early on 10 April, the 14th Panzer Division of Generalmajor Friedrich Kühn broke out of the Zákány bridgehead and drove towards Zagreb.

The 14th Panzer Division continued on, and by 19:30 lead elements had reached the outskirts of Zagreb, having covered nearly 160 kilometres (99 miles) in a single day.

[42] About 09:45, the LI Infantry Corps also began crossing the Drava, but construction of a bridge near Maribor was suspended because the river was in flood.

[43] This crossing point was a partially destroyed bridge, guarded by a single platoon of the 1st Bicycle Battalion of Detachment Ormozki.

This crossing, combined with the withdrawal of the 7th Army's 38th Infantry Division Dravska from the line Slovenska Bistrica–Ptuj, exposed the left flank of Detachment Ormozki.

[42] Held up by freezing weather and snow storms, on 11 April LI Corps was approaching Zagreb from the north,[44] and broke through a hastily established defensive line between Pregrada and Krapina, outflanking the 42nd ID and the remnants of Detachment Ormozki on the left.

[46] The 42nd ID and Detachment Ormozki were cut off north of Zagreb, and those elements that did not disperse to their homes withdrew into the Ivanšćica and Kalnik mountains.

[49] Yugoslavia was then occupied and dismembered by the Axis powers, with Germany, Italy, Hungary, Bulgaria and Albania all annexing parts of its territory.