1st Cavalry Division (Kingdom of Yugoslavia)

The 1st Cavalry Division was a horsed cavalry formation of the Royal Yugoslav Army that formed part of the Yugoslav 1st Army Group during the German-led Axis invasion of the Kingdom of Yugoslavia in April 1941. In peacetime, the division consisted of two cavalry brigades commanding a total of four cavalry regiments, but its wartime organisation specified one cavalry brigade commanding two or three cavalry regiments, along with divisional-level combat and supporting units.

Along with the rest of the Yugoslav Army, the 1st Cavalry Division began mobilising on 3 April 1941, and was still engaged in that process three days later when the Germans began an air campaign and a series of preliminary operations against the Yugoslav frontiers. By the end of the following day, the division's cavalry brigade headquarters and all of the division's cavalry regiments had been detached for duty with other formations of the 1st Army Group. The divisional headquarters and divisional-level units remained in the vicinity of Zagreb until 10 April, when they were given orders to establish a defensive line southeast of Zagreb along the Sava river, with infantry and artillery support. The division had only begun to deploy for this task when the German 14th Panzer Division captured Zagreb. The divisional headquarters and all attached units were then disarmed by armed Croat fifth column groups, or surrendered to German troops.

Background
The Royal Yugoslav Army (Vojska Kraljevine Jugoslavije, VKJ) was formed after World War I as the army of the Kingdom of Serbs, Croats and Slovenes (Kingdom of SCS), when that country was created on 1 December 1918. To defend the new kingdom, an army was formed around the nucleus of the victorious Royal Serbian Army combined with armed formations raised in the former parts of the Austro-Hungarian Empire that joined with the Kingdom of Serbia to form the new state. Many former Austro-Hungarian officers and soldiers became members of the new army. From its beginning, the army, like other aspects of public life in the new kingdom, was dominated by ethnic Serbs, who saw the army as a means by which to secure Serb hegemony in the new kingdom.

The development of the army was hampered by the poor economy of the kingdom, and this continued through the 1920s. In 1929, King Alexander changed the name of the country to the Kingdom of Yugoslavia, at which time the army became the VKJ. The army budget remained tight, and as tensions rose across Europe during the 1930s, it became hard to secure weapons and munitions from other countries. 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. For example, infantry divisions had a wartime strength of 26,000–27,000 men, as compared to contemporary British infantry divisions of half that strength. These characteristics resulted in slow, unwieldy formations, and the inadequate supply of arms and munitions meant that even the very large Yugoslav formations had low firepower. Older generals better suited to the trench warfare of World War I were combined with an army that was not equipped or trained to resist the fast-moving combined arms approach used by the Germans in Poland and France.

The weaknesses of the VKJ in strategy, structure, equipment, mobility and supply were exacerbated to a significant degree by the lack of unity across Yugoslavia which had resulted from two decades of Serb hegemony, and the attendant lack of political legitimacy achieved by the central government. Attempts to address the lack of unity came too late to ensure that the VKJ was a cohesive force. Fifth column activity was also a serious concern, not only from the Croatian nationalist Ustaše, but from the Slovene and ethnic German minorities in the country.

Peacetime organisation
According to regulations issued by the Royal Yugoslav Army in 1935, the 1st Cavalry Division was headquartered in Zagreb during peacetime, and was under the control of Cavalry Command in Belgrade, as was the 2nd Cavalry Division, which was located in southeastern Yugoslavia at Niš. In peacetime, the 1st Cavalry Division comprised:
 * 1st Cavalry Brigade, headquartered in Čakovec near Zagreb
 * 2nd Cavalry Brigade, headquartered in Subotica in the Banat north of Belgrade
 * 2nd Cavalry Regiment, based in Virovitica on the Drava river in Slavonia
 * 3rd Cavalry Regiment, based in Subotica
 * 6th Cavalry Regiment, based in Zagreb
 * 8th Cavalry Regiment, based in Čakovec

Wartime organisation
The wartime organisation of the Royal Yugoslav Army was laid down by regulations issued in 1936–37, which introduced a requirement to raise a third cavalry division for war service. The strength of a cavalry division was 6,000–7,000 men. The theoretical war establishment of a fully mobilised Yugoslav cavalry division was:
 * headquarters and headquarters company
 * a cavalry brigade consisting of 2 or 3 cavalry regiments
 * an artillery battalion of four batteries, one of which was motorised and equipped with 47 mm anti-tank guns
 * a bicycle-mounted infantry battalion with three rifle companies and one machine gun company
 * a signals squadron
 * a bridging squadron equipped with pontoons
 * a chemical platoon
 * a divisional cavalry battalion consisting of two cavalry squadrons, a machine gun squadron, an engineer squadron and a bicycle company
 * logistics units

Each cavalry regiment was to consist of four cavalry squadrons, a machine gun squadron, and an engineer squadron. Shortly before the war, an abortive attempt was made to motorise the 1st Cavalry Division, but this was stymied by a lack of motor transport and the division largely remained a horsed formation throughout its existence. The 1st Cavalry Division was also never equipped with the planned motorised anti-tank battery, and the divisional artillery battalion was largely equipped with World War I-vintage pieces. Two peacetime components of the division, the 2nd Cavalry Brigade and 3rd Cavalry Regiment, were earmarked to join other formations when they were mobilised, so the primary fighting formation of the 1st Cavalry Division was the 1st Cavalry Brigade, commanding the 2nd, 6th and 8th Cavalry Regiments.

Deployment plan
In case of war, Yugoslav planners saw the 1st Cavalry Division forming the bulk of the reserve for the 1st Army Group. The 1st Army Group was responsible for the defence of northwestern Yugoslavia, with the 4th Army defending the eastern sector along the Hungarian border, and the 7th Army along the Reich and Italian borders. The 1st Cavalry Division was to be held as the 1st Army Group reserve around Zagreb. On the left of the 4th Army, the boundary with the 7th Army ran from Gornja Radgona on the Mura through Krapina and Karlovac to Otočac. On the right of the 4th Army was the 2nd Army of the 2nd Army Group, with the boundary running from just east of Slatina through Požega towards Banja Luka. The Yugoslav defence plan saw both armies deployed in a cordon, the 4th Army behind the Drava river between Varaždin and Slatina, and the 7th Army along the border region from the Adriatic in the west to Gornja Radgona in the east. It was envisaged that this reserve would be located in and around Zagreb. The planners estimated that cavalry formations would take 4–7 days to mobilise.

Mobilisation
A general mobilisation was not called until 3 April 1941, out of fear of offending Adolf Hitler. By the time the invasion commenced, the 1st Cavalry Division had only begun mobilisation. According to the Yugoslav historian Velimir Terzić, on 6 April the mobilisation of the division was proceeding slowly due to the low number of conscripts that reported for duty, and the poor provision of animals and vehicles. A large portion of the strength of the division had been earmarked to be detached to one of the formations of the 4th Army, Detachment Ormozki.

The commander of the 1st Cavalry Division was Diviziski General Dragoslav Stefanović. While the divisional headquarters and other divisional-level units were mobilising in Sesvete near Zagreb, the headquarters of the 1st Cavalry Brigade had been designated to command Detachment Ormozki, and the 6th and 8th Cavalry Regiments and the divisional artillery battalion had also been allocated to that formation. This reduced the main fighting elements of the division to a single cavalry regiment (the 2nd), which was mobilising in Virovitica. The rest of the 1st Army Group reserve comprised an independent artillery battalion mobilising in Zagreb, and the 110th Infantry Regiment which was moving to Zagreb from Celje, a distance of 114 km to the northwest. By early morning of 6 April 1941 when the invasion commenced, the 110th Regiment had reached Zidani Most, still some 90 km from Zagreb.

Operations
Stripped of most of its subordinate units, the 1st Cavalry Division remained in reserve near Zagreb during the first few days of fighting. On 10 April, due to the critical situation on the front of the 4th Army, the division was directed to take under its command the 110th Infantry Regiment and the independent artillery battalion, and defend against crossings of the 110 km stretch of the river Sava between Jasenovac and Zagreb, while collecting stragglers and organising resistance. These orders were quickly overtaken by the rapid advance of the 14th Panzer Division to Zagreb when it broke out of its bridgehead across the Drava river at Gyékényes on the Hungarian border. By 19:30 on 10 April, lead elements of the 14th Panzer Division had reached the outskirts of Zagreb, having covered nearly 160 km in a single day. Armed fifth column Ustase groups and German troops disarmed the division and its attached units before they could establish any coherent defence along the Sava.