Against Hitler's Luftwaffe in the Balkans: The Royal Yugoslav Air Force at War in 1941

By Djordje I Nikolić and Ognjan M Petrović

The full story of the service and combats missions of 220 Yugoslav aviators in early 1941.

Immediately following the end of the First World War, the air force of the newly-formed Southern Slav State, the Kingdom of Serbs, Croats and Slovenes, was forced to rely mainly on war-time Serbian Air Service aircraft and material left after the withdrawal of the French Armée de l’Air from the Balkans in 1919/1920. This equipment was supported by the addition of French war surplus stocks which started arriving in 1921.

In 1929 the monarchy changed its name to the Kingdom of Yugoslavia. Then, from 1930, the official name of the air service branch its military was changed to what is commonly known in the West as the Royal Yugoslav Air Force (RYAF). The obsolete First World War aircraft were replaced from 1925 onwards by stop-gap solutions purchased mainly from France, some from the Czechoslovakian Republic as well as from the first domestic factories.

From 1936, the RYAF again began to reorganize and modernize, with the purchase of the most modern aircraft available at that time. These aircraft were imported from the UK, Germany and Italy, some being built under license in domestic factories. During this period the Kingdom of Yugoslavia succeeded, as much as conditions allowed, to equip its air force with the most advanced fighter and bomber types of the period.

For the Kingdom of Yugoslavia, the Second World War started on 6 April 1941. The military coup d’etat of 27 March 1941 and anti-German demonstrations in Belgrade clearly aligned the kingdom with the Allies. That same day, Hitler ordered the implementation of Unternehmen 25 (Operation 25) – the attack against Kingdom of Yugoslavia. Hitler had also secured Mussolini’s support for this campaign, while Hungary, Romania and Bulgaria gave active or passive backing in exchange for territorial claims in Yugoslavia.

Despite all the odds, the airmen of the RYAF fought gallantly in the defense of their homeland, with fighters taking on the German and Italian bombers and their escort fighters – including the Axis types in service with the RYAF.

Eventually, due to the deteriorating situation on the front and the ever-increasing risk of the king and his government being captured, the decision was taken to evacuate by air to Greece. In the summer of the 1941 some 220 Yugoslav aviators gathered in Egypt and continued the fight against Axis, this time in the colors of the RAF. This is the full story of their service and combats in the early months of that year.

• Language: English
• Publisher: Pen and Sword
• Release date: Nov 30, 2023
• ISBN: 9781399088985

Djordje I Nikolić

DJORDJE NIKOLIC was born in Belgrade, Serbia, coincidentally on National Aviation Day. Since early childhood he has been fascinated by all aviation-related matters, always staring up in the sky and regularly visiting aviation themed museums across Europe. His interests are primarily in the Royal Yugoslav Air Force and the history of Belgrade in the period between the two world wars and his collection includes hundreds of original photographs, documents, pilot logbooks and other memorabilia. Djordje graduated in mechanical engineering from the University of Applied Sciences in Aachen, Germany. Having completed his studies in the German language, he was able to research and interpret historical documents relating to the German aircraft in Yugoslav service in the interwar and Second World War period. He is also an avid aircraft modeler and regularly attends local and national shows and contests. Djordje currently resides in Washington State, USA.

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Chapter I

Yugoslav Military Aviation in Peacetime 1918–41

1937–41 modernisation

From 1936 the Vazduhoplovstvo vojske (VV, literally Military Air Force, commonly known as the Royal Yugoslav Air Force – RYAF) underwent a process of reorganisation and modernisation, which reached its peak during the last three years of peace. Major changes took place related to the formation and new designations of units, selection and arrangement of war airfields, adoption of new doctrine, education and training of pilots and other specialists, selection and acceptance of new imported and domestic-built equipment, organisation of the production of indigenous-design and licence-built aircraft, writing of manuals, directions and regulations for aircraft and equipment, and selection and application of new aircraft camouflage schemes and serial numbers. On 16 December 1938 a new war formation was accepted by the Kraljevina Jugoslavija (KJ, the Kingdom of Yugoslavia) – with air regiments consisting of two air groups with two (rarely three) escadrilles. The VV was officially divided into three segments and these were known as Operativno vazduhoplovstvo (OpV, Combat Aviation, i.e. Operational Air Force), whose base units were equipped uniformly with one fighter or bomber type and with a few auxiliary aircraft; Armijsko vazduhoplovstvo (ArV, Army Co-operation Aviation, i.e. Army Air Force), with reconnaissance/observation aircraft, mainly Breguet 197 and 198 biplanes for co-operation with the Royal Yugoslav Army; and Pozadinsko vazduhoplovstvo (PozV, Auxiliary Air Force, i.e. Rear-Echelon Air Force) with trainers and support aircraft.

The modernisation of the VV began in 1937 by purchasing the most modern aircraft of that time. These were imported from the United Kingdom, Germany and Italy, or simultaneously built under British and German licences by local factories. Indigenously designed aircraft types were also built. Modernisation was carried out despite difficult economic conditions and the fact that most European countries were preparing for the upcoming military conflict. One of the most difficult problems for the VV was the lack of aero engines. As the situation worsened, the domestic industry could not fulfil the deliveries of the ordered warplanes. However, the Royal Yugoslav Government and military authorities, as well as local aviation experts, deserved praise for their efforts. They successfully implemented the modernisation plan, which unfortunately was not completed due to insufficient resources and limited time.

From 1937 until the 1941 April War, the VV and the Royal Yugoslav Naval Aviation (Pomorsko vazduhoplovstvo – PV) received a total of 545 modern aircraft, 426 of them imported and 119 built in the country (42 indigenously designed and 77 licence-built). The Third Reich was the largest foreign suplier with a total of 304 aircraft, while Italy delivered 74, the UK 46 and France only two aircraft.

In the period from 1937 to 1941 the KJ succeeded, as much as possible, in equipping the VV with a number of the most advanced fighter types, which were used at the same time by two of the largest air powers, the German Air Force (Luftwaffe) and British Royal Air Force (RAF). Unfortunately, the VV failed to obtain any heavy fighters, and did not complete the process of re-equipment with the planned and needed quantity of aircraft before the war.

International participation

Besides manoeuvres, VV aviators proved their professional flying ability in domestic and international competitions and meetings. The most important domestic competition was the King’s Trophy air race, which was held each 6 September from 1926 to 1936 (except in 1930) in three categories: combat two-seaters, fighters and trainers. An important foreign demonstration was the Circuit of Petite Entente, which was carried out four times between 1927 and 1930. The winner of the first competition was a VV crew flying an indigenously designed Fizir-Maybach prototype built by Aeroplanska radionica 1.VP (AR 1.VP – 1st Air Regiment’s Aircraft Workshop). A Yugoslav crew also won the fourth competition (first and third to sixth places) using the new ‘second-generation’ Breguet 197 bomber biplanes.

The VV also participated at the Zürich International Meetings in 1927 and 1932 in two-seater and fighter categories. In August 1927 a Yugoslav Dewoitine D.9 C1 was the only aircraft that flew over the Alps in poor weather and the crew of a Potez 25 Lorraine won eighth place at the Alps Circuit for military aircraft. In July 1932 a VV pilot won with a Hawker Fury Mk. IA fighter.

Infrastructure

At the beginning of the 1920s, the undeveloped VV infrastructure consisted of several airfields left by the enemy after the First World War, of which the most important ones were at Novi Sad and at Mostar. As a result, construction of eight new airfields started in different regions of the country (Belgrade, Skoplje, Niš, Kraljevo, Zagreb, Sarajevo, Pančevo and Bela Crkva) and was completed at the beginning of the 1930s. These airfields had wide and long grass runways, large hangars of concrete or metal construction, storage areas, workshops and other related facilities. Five airfields were divided between military and civil users. Immediately prior to the 1941 April War, 100 auxiliary war airfields were prepared. In 1936 the VV Headquarters (HQ) was relocated from Petrovaradin to Zemun (from 1919 part of the Belgrade Municipality), to a new building constructed in 1935 that was designed by famous Serbian architects Brašovan and Jovanović.

Training

During the development and constant improvement of the organisation’s peacetime and wartime formation, the VV built and constantly updated its own complex system of continuous personnel training. The pilot officer training was organised in 1919 at Novi Sad and for non-commissioned officers in 1921 at Mostar. Reserve pilots began training in 1922. In total three pilot schools were formed: 1. pilotska škola – PŠ (Pilot school) in Novi Sad (1919), 2.PŠ in Mostar (1921) and 3.PŠ in Belgrade (1928). Three specialised schools were also formed: Vazduhoplovna izviđačka škola (VIŠ – Air Recce School) at Pančevo (1921), Lovačka PŠ (LPŠ – Fighter Pilot School) at Belgrade (1928), and Vazduhoplovna škola gađanja i bombardovanja (VŠGiB – Air Gunnery and Bombardment School) at Bela Crkva, near Vršac (1931) and Parachute School at Pančevo (1939). These special schools provided the training of reconnaissance and technical personnel, meteorologists, paratroopers and other specialists. In June 1940 the Air Force Academy opened at Pančevo. Air officers selected for high-rank duties were trained at the General Staff School, while a significant number of aviators were sent to foreign air forces. From 1919 to 1941 flying schools trained 2,920 pilots for the VV and PV.

Aviation industry in Serbia and Yugoslavia 1923–34

The first indication that it was necessary to create a domestic aviation industry came from Serbian aviation officials during the First World War. The realisation of those ideas was achieved in 1923 due to the urgent need of the Air Force for trainers. Since trainers could not be purchased abroad due to many difficulties and a lack of credit, the Department of Aviation had to organise production in the country, relying on private funds, local experts and workers. Such a move came from the conviction of those responsible in the state and the Army that the successful and independent development of domestic aviation could not be achieved without the country’s own aviation industry, and indigenous designer personnel. It was easier to make such a decision because the production of aircraft at that time, mostly of a wooden structure, could successfully be organised in a craft and semi-industrial manner. A group of experienced engineers and professionals, mostly of South Slavic origin, who gained rich experience in designing and manufacturing aircraft during the First World War in Austro-Hungarian, German and Russian aircraft factories, also contributed to an early appearance of the domestic aviation industry.

Without a doubt, AR at Novi Sad, originating from the Serbian Air Park at the Salonika front, was regarded as the forerunner of the Serbian/Yugoslav aviation industry. It took over some of the hangars and equipment abandoned at the airfield after the retreat of Austro-Hungarian units. In the beginning it overhauled Serbian equipment and captured aircraft and engines, but soon it began to produce complete wing assemblies and other airframe parts. From 1921 several complex conversions of aircraft then in service were realised, and at the end of 1923 a small sample series of Srednji Brandenburg (SB – Mid Brandenburg, a non-licensed copy of the Brandenburg C.1), were ordered and delivered during 1924. Production of that type was later continued by the first two domestic factories.

On 20 November 1923 the first domestic aircraft factory, Ikarus, was established at Novi Sad. In April 1924 the first series of Mali Brandenburg (MB – Small Brandenburg) or Školski Brandenburg (ŠB – Training Brandenburg), a copy of Brandenburg B.I primary trainers, were delivered to the Vazduhoplovstvo Kraljevine Srba, Hrvata i Slovenaca (Air Force of the Kingdom of Serbs, Croats and Slovenes, V KSHS). Flying and technical characteristics were equal to the contemporary foreign aircraft in the same category. That fact led to increased confidence in the aviation industry and local designers and, at the same time, opened a path for further development of aircraft in the country. In April 1924 newly formed Prva srpska fabrika aeroplana Živojin Rogožarski (First Serbian Aircraft Factory Živojin Rogožarski) from Belgrade joined Ikarus, first in the production of parts and soon complete aircraft. By 1928 these two companies had delivered about 100 quality trainers and seaplanes.

The growth of the domestic aviation industry received a significant boost when a crisis broke out in the mid-1920s in relations with the neighbouring Kingdom of Italy. At the beginning of 1926, according to the new programme of increased arming of the KSHS Army, superiors in the administration and the Army decided to order, within five years, over 800 combat aircraft and several hundred trainers. Their production was mostly delegated to the local aviation industry, which thus faced major challenges as it was not sufficiently prepared for independent engagement in that great and urgent work. The solution was found in licence production of the then ultramodern, French-designed reconnaissance-bomber Breguet 19 and Potez 25 biplane types. A new and modern factory for the production of metal aircraft was built at Kraljevo (Central Serbia) in 1927 and was immediately assigned to the Breguet Company. The French firm was committed to both the production of different Breguet 19 versions, with different types of engines, and the training of local technicians and workers for independent production. Starting work in 1928, this factory was known as Fabrika Aviona Kraljevo (FAK – Aircraft Factory Kraljevo, also known as Breguet Plant Kraljevo), and it produced 425 Breguet aircraft in six versions for the VV and 45 for export.

At the same time, for strategic and production reasons, Ikarus was ordered to build a new plant in Zemun, which was also structured for modern aircraft series production. By 1932, 220 Potez 25 A2 biplanes, equipped with domestic-built IAM 9Ad Jupiter radials, had been delivered from the new Ikarus plant. Up to 1931 the old Ikarus plants at Novi Sad built 37 flying boats, designated as IO (Izvidjač Obalni, i.e. Coastal Reconnaissance) and several prototypes, all indigenously designed. During 1928 to 1929 Rogožarski built a series of 32 F.1V (Fizir-Maybach) biplane reconnaissance-trainers, and by 1931, five prototypes developed from the same airframe. In addition, this company also built its own design of an advanced trainer prototype, the AŽR, called ‘Blue-Yellow Bird’.

At the beginning of 1927 the fourth Serbian aircraft factory, Fabrika aeroplana i hidroplana – Zmaj (Aircraft and Seaplane Factory – Zmaj), was created at Zemun. By the beginning of the 1930s, Zmaj had delivered 45 Hanriot H.320 primary trainers, 10 Hanriot H.41H floatplane trainers, 26 Gourdou-Lesseure LGLB fighter-trainers and 3 Dewoitine D.27 C1 metal fighters.

The largest effort was made when two new factories for licence engine production were built at Rakovica, then on the outskirts of Belgrade, which became one of the largest industrial centres in the country. The first factory, Industrija aeroplanskih motora (IAM – Aero-Engine Industry), relied equally on French and domestic capital. This factory delivered 420 air-cooled, 9-cylinder, 420mhp Gnôme-Rhône Jupiter radials between 1928 and 1932. The second factory, Vlajković-Walter, created in co-operation with the Czechoslovak Walter concern, produced 230 air-cooled, 7-cylinder 120mhp Walter NZ/NZR radials between 1929 and 1934. Production of those modern engines, in a country which had not even manufactured any steam engines beforehand, was a major change in the industrial, technical, technological and economic development of Serbia and the entire KJ.

Crisis years

The rise of the domestic aviation industry lasted until 1932, when state orders stopped due to the consequences of the global economic crisis. The relatively high capacities of aircraft factories were hardly used and the number of employed workers was reduced. At these critical moments the state, as the sole buyer, ordered a small annual batch of BH-33E biplane fighters and aircraft overhauls from various factories, attempting to retain the core of professionals and specialised workers for better times. Breguet’s plant at Kraljevo built Bre 197s for export and parts for overhauling the large numbers of aircraft of that type in VV service. The value of the aviation industry was reflected in the large number of indigenously designed types. The first generation of designers, who were active during the 1920s, designed a number of military primary and advanced trainers and seaplanes, of which four types in ten versions were produced in quantity.

Renewed rise and modernisation of the aviation industry 1935–41

A new emergence of the domestic aviation industry began in the mid-1930s, at the time when the rise to power of the Nazis in Germany clearly signalled that a new war was approaching. A substantial share of the necessary modernisation of the VV was again entrusted to the domestic aviation industry. In that new sharing of fighter orders, Ikarus adopted the production of two metal fighters, the licence-built Hawker Yugoslav Fury and the indigenous IK-2, while Rogožarski delivered mixed-construction IK-3 fighters and, in addition, started work on a batch of all-metal Hawker Hurricane Mk. Is. Zmaj also produced Fury fighters, primary and advanced trainers, and was able to deliver 24 Hurricanes mostly prior to the 1941 April War. VV bomber strength was reinforced by Ikarus licence-built Blenheims and DFA Kraljevo-manufactured Do 17Ka-3 bombers.

Until April 1941 all factories were gradually increasing production capacity and the number of employees, introducing new construction technologies for series production with mixed and metal structures and accepting production of new generations of aviation instruments, various components and parts, oxygen and other equipment, parachutes, plywood and other materials necessary for modern aircraft production. Owing to the significant increase in orders and the need for assignment of ever-increasing production needs, new aircraft factories were established in Serbia during that period.

A very important purchase of fighters and bombers for the VV inventory was made from Germany (Bf 109E-3a fighters) and Italy (Savoia-Marchetti SM.79I heavy bombers and three versions of Caproni Libeccio bimotors).

New indigenously designed aircraft

The programme to rely on domestic designers was particularly promoted prior to the war when, due to difficulties in procurement abroad, the government encouraged domestic designers’ activity and the production of numbers of prototypes. From 1938 Rogožarski started manufacturing the legendary IK-3 fighter, and in addition in 1940 built a prototype of the twin-engine R-313 heavy fighter. In the same period, this factory delivered a series of twin-engine SIM XIV-H coastal reconnaissance-bomber floatplanes and SIM XII-H trainer floatplanes. In addition, Rogožarski manufactured SIM X trainers and continued to build its very successful PVT advanced trainer and its floatplane derivative, the PVT-H. During the same period Ikarus built a twin-engine, all-metal Orkan (Hurricane) heavy fighter prototype, while Zmaj also