Shipbucket

Bulgarian Airstrike

Bulgaria’s area of operation was directly west of their border, with the plan that ground forces would squeeze the Yugoslav 3rd and 5th Armies against the Italian army push from Albania. The air target of the Bulgarian Air Force was the 3rd Mixed Air Brigade who’s combat force was Dornier Do 17’s and Hawker Fury fighters. With their new Italian supplied BR.20’s and G.50’s already allocated for the Belgrade strike, the Bulgarian attack force was composed of the ex-Czech fleet of Avia B-71 bombers and B-534 fighters.
Yugoslav listening posts had detected significant activity from Bulgaria before dawn, and elements of 35 and 36 Squadron’s Fury’s had been scrambled on patrol. Initially engaging, the flight of 4 Fury’s were significantly outnumbered by the B-534’s and were unable to break through the fighter screen to get to the bombers.



The Fury’s of 36 Squadron, being based closest to the target at Petrovec, were the first defenders able to arrive in any degree of strength, with another 12 aircraft joining the fray as the Bulgarian bombers reached their target. The Bulgarian and Yugoslav fighters were both evenly matched aircraft, and while the defenders were a highly skilled force, the attackers had been subject to intensive tactical training from their Italian mentors. Neither fighter corps prevailed in the aerial battle, with aircraft losses to both sides, but even with the loss of 2 bombers, the B-71’s were able to hit and cripple the Dornier fleet below them.
As the attack was finishing the Fury’s of 35 Squadron arrived, bringing additional fresh firepower to the defence. Too late to change the course of the battle, the arriving aircraft managed to hit the Bulgarians hard, taking down another 3 retreating bombers. Harrying attacks on the retreat Bulgarians continued, with the Fury pilots remaining airborne until their aircraft were running low on fuel, leading to the fortuitous interception of the Italian bomber force from Belgrade.



Although the airfields were damaged and fully a third of the Dornier fleet was beyond repair, the Yugoslav crews immediately started preparing for a counter strike into Bulgaria.

Raid On The Bay Of Kotor

With Italy’s bomber forces committed to destroying the offensive capacity of the Yugoslav air force, dealing with the seaplanes of the Hydroplane Commands had been left to biplane fighters based in Albania. With planning for the territories post-invasion, specific instructions had been given to the Italian pilots; only aircraft and vessels were targets, all ports and facilities were not to be attacked.
The Fiat CR.42’s of the 160 Fighter Group ranged up the coast as far as Dubrovnik sinking 2 Yugoslav minelayers, old vessels still in service from the Austro-Hungarian navy.
The Yugoslav air assets though were already airborne and patrolling the Adriatic hunting for the expected Italian naval attack, and were not within the interception area of the Italian fighters. The single aircraft lost by the Yugoslav’s was a single Dornier Wal flying boat that had not been scrambled due to a mechanical problem, and was strafed and sunk at its mooring at Dobrota on the Bay of Kotor.

Northern Strikes

Getting airborne before dawn Fiat BR.20’s crossed the Adriatic over Zara and tracked deep into Yugoslavia to hit the Blenheim light bomber force airfields along the Sava River. Flying with the BR.20’s were Breda Ba.88 fighter bombers on the type’s first operational sortie, tasked with attacking the associated fighter airfields of 33 and 34 Fighter Groups.
The BR.20’s struck without opposition, causing significant damage to the unprepared Blenheim’s, but losing 3 aircraft to anti-aircraft fire before retiring.
What was supposed to be the introduction of Il Duce’s premier aircraft into combat was an unmitigated disaster for the Regia Aeronautica. With poor performance from the aircraft already apparent, the hope was that operations in the cool of late winter would assist in identifying potential improvements in the Breda’s design. Fully loaded and fuelled the Ba.88’s started the operation badly; struggling to climb over the Adriatic, gaining altitude at a rate that was disconcertingly slow, and being left behind by the bombers they were supposed to be flying in formation with.
With the assault on the Blenheim airfields the Hurricanes and IK-2’s of 33 and 34 Fighter Groups scrambled but were too late intercept the bombers, but most were airborne and positioned to intercept the inbound Ba.88’s. Although designed to be a world-beating heavy fighter, the reality of the Breda’s performance was well below its on-paper potential, especially when carrying their semi-recessed bomb-loads. Although outnumbered almost 10:1 the Yugoslav fighters easily out flew the Ba.88’s, breaking into their formations as they approached their targets. With the fighters already airborne from their dispersal fields the Breda’s were able to achieve little with their bomb attacks, and even then many aircraft had pre-emptively jettisoned their bombs in an attempt to gain enough performance to dogfight.



While still committing to their bombing runs the Ba.88’s were only able to defend themselves with a manually-operated machine gun in the rear cockpit, leaving them vulnerable to the faster and more agile fighters. Even though fitted with a cluster of 3 heavy machine guns in the nose the Breda’s had neither the speed nor the manoeuvrability to aggressively dogfight themselves into a position to use them offensively.
With the Yugoslav fighters flying almost unopposed through the Ba.88 formations and with no significant ability to defend themselves, the attacking force lost any semblance of military discipline. Seeing their comrades descending in flames, the crews of the outclassed Breda’s started turning tail and endeavouring to head back to Italy, giving up on any attempt to outfight the defenders.
With the mauled Italian force on the retreat the Yugoslav’s kept contact, harrying their erstwhile attackers. Encouraged by their own successes the Hurricane pilots over extended themselves now, leading to their only loss in the combat with 2 aircraft running out of fuel and being damaged while forced landing.

Yugoslavian Defensive Strategy

While Yugoslavia had a nominal army strength of one million men, mobilisation had been continuing at only a very slow rate before the international situation had become critical, while Prince Peter had attempted to not antagonise Yugoslavia’s neighbours. In actuality Yugoslavia had less than 600,000 men in the field by the time of the invasion, and even then supply problems meant that many units were not combat capable. Only the Third Army facing Albania, and the Coastal Defence Command along the Dalmatian coast were near to full mobilisation status. But probably the biggest weakness of the Yugoslav Army was the entrenchment of the Serbia-focus of the Yugoslav state in general, with a total of 163 of 165 army generals being Serbians.
Yugoslav defensive strategy had called for a fighting withdrawal into the mountainous interior and towards the Greek border, to allow for a prolonged campaign and the potential of Anglo-Greek assistance. However the idea of abandoning the nation’s vital core was unpopular, and a revised War Plan R-41 was issued in early March 1941. The new battle plan called for the defence of every frontier crossing point along the almost 3000kms of Yugoslavia’s borders. A strategic reserve was included in the plan, but by the time of the attack had not been created. Defensive positions in depth were not considered, only individual frontier fortification points, but those without heavy artillery.
The Yugoslav army was formed into 3 Army Groups, an independent army, and the Coastal Defence Command, with air support for each Group. The First Army Group was responsible for the northern sector, with the 7th Army deployed along the Italian German borders around Ljubljana, and the 4th Army along the northern Hungarian border around Zagreb. The Second Army Group was to defend the central sector, the 1st Army positioned in the Banat and the eastern Hungarian border, and the 2nd Army along the centre of the Hungarian border. The Third Army Group covered the south of Yugoslavia, with the 3rd Army covering the whole of the Albanian border, and the 5th Army guarding the Bulgarian border. The independent 6th Army protected Belgrade and the Romanian border, and the Coastal Defence Command was responsible for the whole of the Adriatic coast line.
Yugoslav defence had no depth, with border guards at the actual frontier and the regular and territorial army units at their staging points near to the border. Behind these troops there were no reserves, and only a weak transportation network and insufficient motorised transport limited the ability for rapid redeployment of units to sectors under assault.

Defence of Southern Yugoslavia

The Yugoslav Third Army Group was based in southern Yugoslavia, with the Third Army responsible for the length of the Albanian border and the Fifth Army defending along the Southern Romanian and Bulgarian borders. With the air attacks on Belgrade communications with the Yugoslav central command rapidly degenerated into intermittency, however reports of air attacks from all over the country left Armijski đeneral Milan Nedić in no doubt that a full scale invasion of Yugoslavia was under way and all units were ordered into a war-time alert status.
Within the Third Army Group’s area of responsibility the air attacks had all come from only Bulgarian aircraft, so the orders were given for the Fifth Army units to deploy from their staging areas to the forward border positions in anticipation of an attack by Bulgarian ground forces, while the Third Army were only on alert to monitor the Albanian frontier. But Bulgarian troops had already crossed the frontier in three places; without opposition at the village of Uzem on the road to Skopje, and engaging with the border defences at Tsarevo Selo and Novo Konjarevo.
Although the Yugoslavs’ initially mounted a determined defence, the frontier troops were only able to mount a delaying action, not in positions or strength to repel a full scale invasion. The defensive fortifications were mostly little more than concrete pillboxes armed with machine guns connected by open trenches without artillery support. The lack of anti-armour weapons was of no importance in the battles though, as the Bulgarian troops were without armour and motorised only through the use of Italian supplied soft-skinned trucks.
Restricted to movement on the roads due to the rough and hilly terrain, the Bulgarian motorised columns were stopped by heavy machine gun fire from the small frontier forces at the border. But these delays had been expected in the Bulgarian war plan, and in support of the Bulgarian ground troops PZL.43’s attacked the Yugoslav positions. While the German Stukas had had little effect on the French defensive positions some months earlier, the Yugoslav positions were not constructed to the same standards, and were not able to withstand the air assault. Within 2 hours all had been border positions had been neutralised allowing the Bulgarian columns to continue their advance.

Italian Advance From Albania

While the Yugoslav’s had surrounded Albania with their strongest troops, the expectation was that the Italian advance would be focussed on the Dalmatian coast with a push up towards Šibenik. Instead the Italians had their ground attack from Albania focused to the north towards Belgrade, pushing out from the Albanian border town of Kukës towards Prizren, where the Yugoslav 31st Infantry Division were centred. As the advance through to Belgrade was through generally flat terrain the Italian force included a significant motorised component.
The Yugoslav border guards were quickly overwhelmed, and the spearhead of the new Autoblinda AB 40 armoured cars lead the advance to Prizren. Being on a major road into the heart of Yugoslavia, defences had already been established around the town and those elements of the 31st Infantry Division that had already mobilised were in position before the first Italians had crossed the frontier. Although not equipped with heavy weapons, the Yugoslav troops greeted the Italian force with withering fire and blunted the assault.



Probing attacks from Italian assault pioneers during the morning failed to break the Yugoslav defences, leaving the whole of the Italian advance stalled. By noon the situation for the Italian advance had become critical, as although Italian infantry had moved into positions around the north and south of the town, no roadways were controlled to allow the advance of Italian vehicles. Buoyed from their successful strike on the Yugoslav bomber force at Mostar, Italian Junkers Ju 87’s were retasked to break the Yugoslav positions.
Airborne from their fields in Albania, the Ju 87’s were able to launch multiple strikes on Prizren with the depleted Yugoslav Air Force not able to mount a defence. Screaming down on the Yugoslav positions the Italian Stukas made short work of the Yugoslav emplacements, with the tattered defenders falling back into the town itself. But the victory was a qualified one for the attackers, as the damage caused to the roads now created a new bottleneck for the Italian column.
Halted now, the Italians scrambled to bring forward engineers to effect repairs, while infantry units continued with their attempts to penetrate into Prizren.

Defence Of The Dalmatian Coast

Expecting an Italian attack on Šibenik from the sea as the start of hostilities, the aircraft of the Yugoslav Hydroplane Commands were on patrol immediately it was light enough for the seaplanes to get airborne. A flotilla of the destroyer Beograd and 10 torpedo boats had been dispatched before dawn and were already enroute to Šibenik from their base at Kotor to defend the city.
As the day dawned, like every other Command, the Coastal Command and Hydroplane Command were without any direct orders from Belgrade, but combat information being radioed in from all over the country painted a bleak picture of a massive assault from multiple directions. Remaining undeployed units were ordered to Kotor, now that the gloves were off defence of both the northern city and southern naval base was vital.
Arriving shortly after the CR.42’s had demonstrated Italian air superiority over Kotor, the 3 Yugoslav R-313’s arrived at Podgorica and were immediately prepared for combat patrol. With the seaplanes headed north, the R-313’s were tasked into the Adriatic to the south-west. Flying in a tight wing of 3 aircraft the R-313’s soon spotted an Italian CANT Z.501 of the 142nd Reconnaissance Flight. Although designed as light bombers, the R-313’s were as agile as contemporary fighters and armed with a single offensive 20mm Hispano-Suiza HS-404 cannon. Thoroughly outclassing the Italian flying boat, the three R-313’s sped in to attack the Z.501. A large target for a single-engined aircraft, the R-313’s shattered the Italian’s engine and shredded its wings, forcing it down with the loss of all crew.



Further patrols over the Adriatic were continued without further contacts that day, and although additional Italian fighter sweeps were mounted from Albania, no ground movement was noted west from Albania. By the evening no Italian move across the Adriatic had been seen either, with the Yugoslav south-western quadrant being a relative backwater to the conflict elsewhere.

Italian Advance On Ljubljana

The Yugoslav-Italian border was the most heavily, and effectively, defended sector of the Yugoslav border. This was though a strength relative to the weakness of the rest of Yugoslav fortifications, as the Yugoslav’s Rupnik Line was at best only partially constructed (it was only expected to be completed in 1947) and manned mainly by border guards and the army reservist construction workers who were building it.
Like the other Yugoslav army units, the mobilisation of the 7th Army was very patchy, and possibly more importantly vehicles and transport animals were even less prepared for deployment. But this was more than balanced by the manpower of the reservist construction workers at the front-line, although weaponry was in short supply.
Italy’s initial push eastwards was of necessity restricted to the roads and passes, with slow progress in the rugged terrain. Weak though the Yugoslav defences were, their positioning at pinch points in the limited access routes towards Ljubljana made progress almost impossible for the Italians, and what was hoped to be a rapid push through ground to a halt.
In the air the remaining Blenheims of the 8th Bomber Regiment supported by the elderly Breguet Br.19’s of 6th Reconnaissance Group struck at the Italian columns and pressed further into their staging areas, finding themselves with temporary air superiority while the Italians rearmed and refuelled. But as the Fairey Battles of the RAF had discovered over Luxemburg before them, a handful of light bombers have little effect on traffic stalled in a forest.



Meanwhile the Hurricane fighter units positioned further east along the German border spent the day flying patrols along the northern frontier, waiting for a German assault, and so played no part in the day’s fighting. Despite the efforts of both sides, as evening fell on the 27th the Italian force had not pushed much further than their initial contacts with the Yugoslav defences, while the Yugoslav’s had not been able to stem a steady flow of Italian troops towards the front. The Yugoslav’s though were still struggling to mobilise and forward deployments were severely hampered by the actions of the Italian air force.

This AU is progressing very nicely.

Horrified to realise that I'd left a gap of a whole year posting here while falling down a rabbithole drawing Soviet tanks, French helicopters, American jets, Hungarian turboprops, German flying boats ...