Yugoslav order of battle for the invasion of Yugoslavia The Yugoslav order of battle for the invasion of Yugoslavia includes a listing ( or order of battle ) of all operational formations of the Royal Yugoslav Army ( , VKJ ) , Royal Yugoslav Air Force ( , VVKJ ) and Royal Yugoslav Navy ( , KJRM ) at the time of the World War II invasion of that country in April 1941 . The VKJ consisted of 33 divisions and 10 independent brigade s , but due to tentative and incomplete mobilisation , only 7 divisions and 6 smaller formations were at close to fighting strength and in their planned deployment locations when the German - led Axis assault commenced on 6 April 1941 . The Yugoslav defence plan involved placing the bulk of its land forces close to its borders , with very limited strategic reserves in depth . Almost all of the divisions that had been effectively mobilised were concentrated in the 3rd Army Group deployed in the east of the country along the Romanian and Bulgarian borders between the Iron Gates and the Greek border . Most of the heavy weapons and armoured vehicles available to the VKJ were obsolete , most formations were heavily reliant on animal - powered transport , and the VKJ possessed only 50 tank s that could engage front line German tanks on an equal basis . On 6 April 1941 , the VVKJ had been almost completely mobilised , and consisted of 4 air brigades with more than 400 aircraft of Yugoslav , German , Italian , French and British design , including less than 120 modern fighter aircraft , and less than 110 modern medium bomber s . Other than a small number of locally made Rogožarski IK - 3 fighters , almost all the modern aircraft available to the VVKJ were of German , Italian or British design for which limited spares and munitions were available . The KJRM consisted of a flotilla of river monitor s based on the Danube and a small fleet based in several ports along the Adriatic coast . The blue - water navy centred around a destroyer leader , three smaller destroyer s , four obsolescent submarine s and a gunboat , supplemented by minelayer s and torpedo boat s . Most of the smaller vessels in the Yugoslav fleet had been inherited from the defeated Austro - Hungarian Empire following World War I and were obsolete . Royal Yugoslav Army . At the time of the invasion , the Royal Yugoslav Army ( , VKJ ) consisted of 17 regular and 12 reserve infantry divisions , 6 combined arms brigade s , 3 regular cavalry divisions and 3 reserve cavalry brigades , 1 fortress division and one fortress brigade . There were also 23 frontier guard battalions , a few frontier guard regiments and some fortification troops . The Yugoslav defence plan positioned almost all land forces close to its borders , with very limited strategic reserves in depth . The VKJ was heavily reliant on animal - powered transport , mainly ox en , and had only 50 relatively modern Renault R35 tanks that could fight German tanks on an equal footing . The VKJ was organised into the 1st , 2nd and 3rd Army Group s , the independent 6th Army and the Coastal Defence Command . As mobilisation had been tentative and partial , many divisions were still in the process of mobilisation on 6 April 1941 . The VKJ order of battle on 6 April 1941 is detailed below : 1st Army Group . The 1st Army Group was commanded by General Milorad Petrović . It consisted of the 4th Army of General Petar Nedeljković , responsible for the Yugoslav - Hungarian border and deployed behind the Drava between Varaždin and Slatina , and the 7th Army of General Dušan Trifunović , which was responsible for the defence of the northwestern border with Italy and the Third Reich . The Army Group Reserve was located around and to the south of Zagreb . 2nd Army Group . The 2nd Army Group was commanded by General Milutin Nedić , and consisted of General Milan Rađenković ' s 1st Army , responsible for the area between the Danube and the Tisza , and the 2nd Army of General Dragoslav Miljković , responsible for the border from Slatina to the Danube . There was no Army Group reserve , but the 2nd Army was to constitute a reserve of one infantry division deployed south of Brod . 3rd Army Group . The 3rd Army Group was commanded by General Milan Nedić . It consisted of General Ilija Brašić ' s 3rd Army , responsible for the border with Albania between Lake Ohrid to Lake Skadar , and the 5th Army of General Vladimir Čukavac , which had responsibility for the Romanian and Bulgarian borders between the Iron Gates and the Greek border . The Army Group Reserve consisted of one infantry division deployed around Skopje . 6th Army . The 6th Army was commanded by General Dimitrije Živković , and was originally intended to form the strategic reserve for the VKJ . It was deployed around Belgrade and in the Banat region east of the Tisza . It held two infantry divisions in reserve in the lower Morava valley . Major equipment . In April 1941 , a significant amount of obsolete equipment was in service with the VKJ , much of which was of World War I vintage . For example , of the 7 , 000 artillery pieces , less than 60 per cent were relatively modern , and only 50 of the tanks on hand were of comparable quality to front line German tanks . The army inventory included the following major items of equipment : Royal Yugoslav Air Force . In April 1941 , the Royal Yugoslav Air Force ( , VVKJ ) was organised into a headquarters , four air brigades and one naval brigade . Peacetime headquarters locations are given for each regiment , but it is assumed that they redeployed to be closer to their subordinate groups . In addition to operational units , the VVKJ had a pilot and bomber school at Mostar with a total of 13 modern aircraft , and a test group at Kraljevo with three aircraft . Air Force Headquarters . VVKJ headquarters was located at Zemun , and had two air groups under its direct command . Sources vary on the exact deployment location of one of the groups , and also vary regarding some details of the number and type of aircraft available at the time of the invasion . 1st Fighter Brigade . The headquarters of the 1st Fighter Brigade was at Zemun . Sources vary on the exact deployment locations of the two fighter regiments and their respective fighter groups , and also vary regarding some details of the number and type of aircraft available at the time of the invasion . 2nd Mixed Air Brigade . The headquarters of the 2nd Mixed Air Brigade was at Nova Topola . 3rd Mixed Air Brigade . The headquarters of the 3rd Mixed Air Brigade was at Stubol . 4th Bomber Brigade . The headquarters of the 4th Bomber Brigade was at Ljubić . Naval Air Force Headquarters . The headquarters of the Naval Air Force was located at Kaštel Lukšić . Aircraft types . Sources vary on the exact numbers of aircraft in the Royal Yugoslav Air Force inventory in April 1941 , which included aircraft types of Yugoslav , German , Italian , French and British design . Estimates of the number of aircraft available range from 405 to 459 . Of these , between 87 and 117 of the fighter aircraft were of modern design , the remainder were not capable of meeting front line Axis aircraft on close to equal terms , and were therefore considered obsolete . Significant numbers of bomber , reconnaissance and naval aircraft were also considered obsolete for the same reason . The most detailed figures available show the following numbers of aircraft by type . Between 6 and 17 April 1941 , the VVKJ took receipt of additional aircraft , including eight Hawker Hurricane Mk Is , six Dornier Do 17Ks , four Bristol Blenheim Mk Is , two Icarus IK - 2s , one Messerschmitt Bf 109E - 3 and one Rogožarski IK - 3 . Royal Yugoslav Navy . The Royal Yugoslav Navy ( , KJRM ) was small , with its largest ships being an obsolete former German light cruiser ( used as a gunnery training ship ) , one destroyer leader , and three smaller " Beograd " - class destroyers . It also included four submarine s , a gunboat , and four river monitor s . At the time of the invasion it included the following vessels :