Shipbucket

Yugoslavia In Early 1941

Although in late 1939 Croatia had been given control of the Yugoslav littoral and granted autonomy within Yugoslavia this had not soothed ethnic tensions, rather it had fuelled calls for full Croatian independence from Croat leaders, and increased Serb influence in Bosnia and Herzegovina from Serbs.
Italy capitalised on the internal tensions within Yugoslavia, providing clandestine financial and material support for Croat nationalist groups, while Bulgarian agents worked to destabilise south-eastern Yugoslavia. The Italian media commenced a hostile media campaign against Yugoslavia, and especially Serbian interests, while Italian claims on the Dalmatian coast were pushed and emphasised. To try and counter Italian ambition, Prince Paul attempted to forge closer defensive relations with both Britain and Germany. With Yugoslavia’s economy being closely tied in to Germany’s, and being deeply committed to the defence of Greece, Britain was not willing to make any formal commitments to the defence of Yugoslavia.
Germany needed the resources of Yugoslavia and so keeping the country at peace was very much in her own interests. Although prevented by the Armistice from deploying any troops outside the borders of the Reich, bolstering Yugoslavia’s military with equipment exports to dissuade Italian aggression was not restricted. However, faced with the very real possibility that any aircraft supplied to Yugoslavia would end up being deployed against the Reich, Germany was not willing to provide aircraft to Yugoslavia. Instead surplus DB 601 engines were made available. The engines were gratefully accepted, and Yugoslav aircraft production was intensified.
Supplies of British Merlin engines had already become problematic, which had meant that the planned Hurricane production had been lethargic with the aircraft only being completed at the Zmaj factory, while at Rogožarski airframes accumulated without engines or armaments. In response the first production aircraft had already been minimally reworked to fit an ex-Bf 109 DB 601 engine. The initial testing had been successful, and production was immediately ramped up to take the new engines shipped from Germany, with new Hurricane LVT-1’s now coming from both the Zmaj and Rogožarski factories. Apart from the new engine and mountings, the modification to the basic design was minimal, and so update kits were able to be pre-assembled, allowing Yugoslav Hurricanes to be converted to LVT-1’s as they were returned to the factories for overhaul.
At Rogožarski the order for 15 R-313’s was actualised on the basis of the evaluation already conducted by the Royal Yugoslav Air Force. The sticking point for production was availability of the Walter engines. Enough engines remained in stock to construct only an additional 3 aircraft, and with the supply of DB 601’s work commenced on re-engineering the design to accommodate the significantly higher horsepower German engines.
After the failure of Fall Gelb, Germany’s Panzer I and II light tanks had been retired from service. The plans to repurpose the chassis’ as anti-tank and anti-aircraft platforms had had varying degrees of success, but still many hundreds remained in storage. Germany now took the chance to sell 80 surplus vehicles to the Yugoslav army. With most of the country being unsuitable for motorised warfare, Yugoslavia had not concentrated on developing a mobile tank force, but rather used small armoured units for defence of the major urban centres. The new Panzers were formed into a new Third Battalion, with companies assigned to the Second Army in Vinkovci, the Fifth Army in Niš, the Seventh Army in Ljubljana.

Prelude To Invasion

Italian agents and Ustaše agitators had infiltrated into Yugoslavia, and from the beginning of March commenced a programme of acts of civil disorder and attacks on police and border posts. With the warming weather of spring, actions culminated in an aggressive demonstration in Šibenik on Sunday 20th April, calling for the return of the city to Italy. With attacks on government buildings, troops from the Yugoslav Coastal Defence Command fired on the protestors and broke up the mob.
The next day the Italian press upped the rhetoric against Yugoslavia, while Ustaše propaganda played the incident as the Yugoslav government firing on ethnic Italians demonstrating support for Croatian independence. Across the country incidents and actions against Yugoslav government institutions increased. With a background of increasing domestic instability, Prince Paul ordered a slow and discrete mobilisation, hoping to be able to maintain order within the country while not being seen to be taking aggressive steps that may have triggered external conflict.
On Thursday 24th April Major Vladimir Kren of the Yugoslav air force took a Potez XXV light bomber and defected to Trieste in Italy. Declaring himself a member of the Ustaše, Kren brought with him details of the Royal Yugoslav Air Force disposition and dispersal airfields, as well as the air force communication codes, the location of Yugoslavia's troop mobilisation centres and air-raid shelters in Belgrade. Kren’s actions caused consternation within both air force and governmental circles in Yugoslavia, while in Italy the details provided were rapidly integrated into Italian war plans.



On the evening of Saturday 26th, Italy’s ambassador to the Court of Prince Paul, Francesco D'Archirafi, presented an ultimatum, rejecting the Treaty of Rapallo and demanding ceding of the port city of Sebenico, under threat of retaliatory action.

Invasion of Yugoslavia

The Italian demand was patently unacceptable to Yugoslavia, with the city now an integral part of Yugoslavia and a major naval base. The Yugoslav general staff were hurriedly called in for crisis meetings as Italy had now dropped the façade and announced its intention to take military action against Yugoslavia. Emergency communiques were drafted and sent to Britain and Greece with frantic requests for political and military assistance. General mobilisation was ordered, and expecting action against Šibenik, the army’s Coastal Defence Command and the navy’s Central Sector and 2nd Hydroplane Command were placed on alert.
However, the Italian ultimatum was no more than a ruse, and the Yugoslav response was of no consequence, as the Italian led attack was initiated before dawn on Sunday 27th April.

Decapitazione

Before dawn Italy’s heavy bomber force in southern Italy became airborne, entered formations and started tracking northeast over the Adriatic. At the same time at airfields in western Bulgaria the bombers and fighters of the Bulgarian Air Force were warming their engines in the pre-dawn chill. The target for both forces was the Yugoslav capital of Belgrade. Shortly after Italy’s medium and dive bombers became airborne, picking up their fighter escorts, and setting multiple courses for the identified Yugoslav airfields.
Yugoslav listening posts detected the heavy bombers crossing the coast and the Bulgarians crossing the border before dawn, and alerts were passed to Yugoslav fighter units throughout the country, although in the dark and with no further information few units sent up air patrols. As dawn broke the first wave of the Bulgarian Fiat BR.20M’s and their G.50 bis escorts arrived overhead Belgrade and started their bombing run over the city. In response the 32nd and 51st Fighter Groups scrambled from their fields around Belgrade to intercept with their Messerschmitt Bf 109’s and Rogožarski IK-3’s. from their top-cover position, the Bulgarian G.50’s dived in to engage and protect the bombers.
The Yugoslav pilots flying in basic wingman pairs climbing towards the bomber formations, rapidly closing from below and to the rear. The first aircraft to engage was 2nd Lt Dušan Borčić in an IK-3 from 51st Fighter Group, with a Bulgarian bomber being crippled and brought down before releasing its bombload. Repositioning for a second attacking run, Bulgarian fighters with the advantage of speed and height intercepted the IK-3’s, bringing down Borčić as the first Yugoslavian combat loss over Belgrade.



With the initial dynamic advantage of height and speed the more numerous Bulgarian fighters had advantage over the Yugoslav defenders, but once combat had been entered the G.50’s poorer performance and weaker armament became obvious. Both the bombers and fighters supplied to Bulgaria from Italy were older models and were now outclassed by the more modern fighters operated by Yugoslavia. The BR.20M’s were slow and lacked sufficient defensive armament to adequately protect themselves, while the G.50’s struggled with individual combat against the Bf 109’s and IK-3’s. The Bulgarian bombing run over the city centre of Belgrade was successful though, with significant damage and fires starting through the city. But the raid had come at a high price for the attackers, with 7 bombers lost over the city or during the return their fields in Bulgaria, while 9 fighters would not fly again.
The Yugoslav fighters had also suffered losses, and with the departure of the Bulgarian strike force the defensive force broke contact and retired for their home fields. The Italian planners had gambled on this, and the Italian heavy bomber force’s arrival had been timed exactly for this window in defensive screening. Without any fighter escort, the CANT Z.1007bis bombers from southern Italian bases were vulnerable and the crews on edge, but no fighters stationed in the vicinity of Belgrade had been held in reserve and all were now frantically committing to rearming and refuelling.
The inbound force was formed into two waves; the 47° Stormo aircraft positioned to the northeast of the city, and the 50° Gruppo aircraft positioned to the southwest. In the clear morning skies the Danube and Sava Rivers formed perfect lead-in lines to the centre of the city and the Belgrade Fortress at the river’s confluence. Flying along the Danube the growing smoke from the fires in the city marked the target for the first wave, and with precision the 1007’s unloaded their bombs in the centre of the city unopposed and unharmed, and set course home for Grottaglie.
Minutes after the first wave finished their run, the second wave following the Sava River, struck Belgrade from the southwest. Delivering their bombload in perfect bombing conditions, the aircraft of 50° Gruppo rained further destruction on Belgrade against no fighter opposition, and turned back for Italy.
Tracking south-westwards towards home, the retreating CANT’s passed near the airfields of the Yugoslav 5th Fighter Regiment. After their own gruelling morning of combat against Italian aircraft their Fury’s were returning for refuelling and rearming and were in no position to take on the high altitude heavy bombers rapidly heading back to Italy. Several aircraft did though break from their landing plans, and climbed to engage in forlorn attempts to strike at the aircraft that had devastated Belgrade. One Fury was able to make an attacking run on a Z.1007, but was enable to follow up as fuel starvation ended the attack and led to the Fury being damaged in a forced landing in a farmer’s field. A second aircraft managed to engage, with more fuel but with less ammunition. In desperation the Yugoslav pilot flew his Fury into the tail of one of the CANT’s, crippling both the bomber and his own aircraft. Losing directional control the bomber dropped from formation, with the Italian pilot barely able to make a controlled crash in the Yugoslav countryside below. With his Fury now little more than a poor glider, the Yugoslav pilot followed the CANT, putting his Fury down beside the Italian wreck and at the point of his service pistol capturing the crew.

Gambizzazione

Italy’s pre-emptive aerial bombardment was a two-phase operation, with the strike on the Yugoslav government and command structures in Belgrade being only one phase. Simultaneously Italy initiated the second phase with multiple strikes at the Yugoslav air force at their bases before they could be used against the invading land forces. From airfields in Albania and north-eastern Italy, Italian medium bombers and fighters became airborne at dawn heading for Yugoslav bases, while overhead the heavy bombers were tracking for Belgrade.
Although the threat of Germany joining the conflict on either side was considered to be very low, to minimise the potential for friendly-fire incidents Italy’s Junkers Ju 87’s had all been freshly repainted into Italian-style camouflage. With their new schemes barely dry, the Junkers Ju 87’s of 101 Dive Bomber Group departed Tirana and formed up with Fiat G.50 fighters and flew north towards Mostar, as the home of both the 81st Bomber Group and the Air Training School was both a command and a combat target.
Just after midnight orders had been relayed from Belgrade to base command at Mostar. The 4 Rogožarski R-313’s of the Training School were seconded to the 3rd Hydroplane Command, placed on wartime alert, and ordered to depart for Podgorica at first light, while the rest of the command was not placed on alert but ordered to prepare for dispersal to secondary airfields. The R-313’s and their crews worked through the night preparing their aircraft, and spent the last of the pre-dawn darkness warming their engines. With the sky finally glowing in the east, the R-313’s departed and formatted to fly together at low-level to the southwest. Behind them they left the base’s Savoia-Marchetti SM.79’s and fighters lined up awaiting further orders, with fuel and ammunition trucks standing by.
As the Yugoslav ground crews started to relax after the frantic energy of the night, the Italian strike force arrived overhead with the base presenting a text-book bombing target. With no advance warning the Ju 87’s dived down onto the Yugoslav flight line, shattering the parked force of Savoia-Marchetti SM.79’s. With no fighter defence airborne, the G.50’s joined in the carnage, strafing the grounded aircraft and facilities. With munitions expended and the airfield blazing, the Italian strike force reformed and returned to Albania without loss.



Refuelling and rearming, by 11 am the strike force returned to Mostar completing the devastation, removing the airfield and its flight units from any further role in the battle.

Amazing work on camo

Indeed, very well executed!

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AU Projects: | Banbha et al. | New England: The Divided States
Blood and Fire

Italian Strikes On Central Yugoslavia

With the Yugoslav air force having a significant SM.79 bomber force, almost all still painted in their delivery schemes of Italian camouflage, Italy made a decision not to send any of their own SM.79’s into battle over Yugoslavia. This allowed a directive that any SM.79’s encountered were hostile and were to be engaged without further confirmation of nationality. This restriction did not unduly restrict the Italian operational planning though, as sufficient Fiat BR.20’s were available to fill the Italian medium bomber force requirement.
A large strike force of Fiat BR.20’s and escorting Macchi C.200 fighters had also set out from Albanian bases, to target the Yugoslav bomber and fighter units dispersed around Kragujevac. This time however Yugoslav Hurricane’s were on patrol and the element of surprise was not on the Italian’s side. The initial combat was entered with numerical superiority for the Italian fighters, but Knić was home to 2 fighter groups of Bf 109’s and Hurricanes, and the attack required crippling that threat, but the Italian strategy was fixated on the bomber fields of at Gorobilje and Preljina, with the fighters at Knic relegated to a secondary target.
Under their regimental HQ at Mostar, the 7th Bomber Regiment commanders had seen the orders passed to the base command at Mostar and had issued orders to prepare their SM.79’s for further orders too. The aircraft of the 66th and 67th Bomber Groups were now arranged on their airfields awaiting orders in the early morning, exposed to the arrival of the Italian bombers overhead.
While the C.200’s parried the Hurricane’s, the Italian bombers cut a swathe of destruction through the parked Yugoslav aircraft, but at Knić the situation was very different. With the call of the initial interception of the Italian strike force the Messerschmitt’s of 31 Fighter group, and the Hurricanes of 52 Fighter Group had both starting scrambling. Although bombs were soon falling on the field an additional 12 fighters, a mix of Messerschmitt’s and Hurricanes, were able to take to the air and join the melee.



While the fighter types were fairly evenly matched for performance, the Italian aircraft were at a disadvantage with regards to firepower and the Yugoslav defenders were able to cause more damage in individual combat. Once through the fighter screen the Yugoslavs found the Fiat bombers were also under armed and with poor armour, but even with a kill ratio of 2:1 numbers were the telling factor, and the defenders suffered a heavy percentage of losses on the ground and in the air. The attacking force was hurt, but the defending fighters suffered a more critical loss in numbers. The Yugoslav air force’s offensive capability in the central sector had been virtually eliminated, while the fighter defence had been reduced by more than half.

Nice, but you ought to credit Jabba, not me.
(I did some Hurricanes, based on Jabba's base drawing, but made some changes, and I see none of them - http://shipbucket.com/vehicles/5672/file )

Thanks @eswube, corrected