Germany attacks Yugoslavia

6 April 1941 was Palm Sunday for Catholics. At 5.15 a.m. German troops crossed the borders of the Kingdom of Yugoslavia without a declaration of war or an ultimatum, and at around 6.30 the first wave of Luftwaffe bombers appeared over Belgrade. Operation Strafgericht (“Judgement” or “Punishment”), as the raid on the Yugoslav capital was named, was to be Adolf Hitler’s revenge for the coup of 27 March, which had overthrown the government that two days earlier had signed the accession to the Tripartite Pact. That same morning the German 12th Army struck from Bulgaria at Yugoslavia and Greece simultaneously. So began the war that the Yugoslavs called the April War. It lasted eleven days and ended in the capitulation of the army, the partition of the state and an occupation that was among the bloodiest in Europe.

Some chronologies state that on 6 April the invasion was begun by German, Italian and Hungarian forces “passing through Romania and Hungary”. On the first day, however, only Germany attacked: from Bulgaria, from former Austria, from bridgeheads in Hungary and, to a limited extent, from the Romanian Banat. For the first few days the Italians confined themselves to air raids and artillery fire, and went over to the attack on 11 April. The Hungarian army crossed the border on the same day. Chronologies also state under 7 April that the Luftwaffe “begins a two-day attack on Belgrade” and that Hitler is “enraged by Yugoslav resistance”. The raids, however, began at dawn on 6 April and continued on 7 April, and according to some historians for a day longer still. Hitler’s fury, moreover, was not a reaction to resistance during the fighting but to the coup in Belgrade itself: he had announced the destruction of the capital as punishment for its “treachery” as early as 27 March.

Ten days of preparation

News of the coup reached Berlin on the morning of 27 March. That same day Hitler told his commanders that Yugoslavia must be destroyed “militarily and as a state”, without waiting for assurances of loyalty from the new government, and signed Directive No. 25. In it the Luftwaffe was ordered to destroy Belgrade by “continual day and night attacks”. Within twenty-four hours the army staff had prepared a plan of campaign, which was merged with the operation against Greece that had been in preparation for months. On 29 March in Vienna the deputy chief of the general staff, General Friedrich Paulus, went through the timetable with the army commanders. It was agreed that the air raids and the attack from Bulgaria on Yugoslavia and Greece would begin simultaneously on 6 April, the advance of the panzer group from the Sofia area on 8 April, and the main thrust from the north a few days later. On 3 April Hitler issued Directive No. 26, which set out the division of tasks and promised Hungary territorial gains.

For ten days the Wehrmacht moved to the Balkans troops that until recently had had nothing to do there. Some six hundred aircraft were brought in from France, Africa and Sicily. Divisions travelled by rail to Austria and Hungary, some of them arriving only after the war had begun. Field Marshal Wilhelm List’s 12th Army, which had been standing in Bulgaria since the beginning of March ready to attack Greece, had to regroup within a few days so as to turn part of its forces west against Yugoslavia. Hitler also courted allies. He promised Hungary’s Regent, Miklós Horthy, Bačka and the Banat. The prime minister, Pál Teleki, who in December 1940 had signed a treaty of “eternal friendship” with Yugoslavia, could not reconcile himself to taking part in the attack and took his own life on the night of 2–3 April. To Mussolini Hitler promised the Adriatic coast, and to Bulgaria Macedonia.

In Belgrade General Dušan Simović’s government still deluded itself that war could be avoided. It did not renounce the Tripartite Pact and delayed general mobilisation so as not to provoke the Germans. Mobilisation was ordered only at the beginning of April, and on 5 April, the day before the attack, a treaty of friendship and non-aggression was signed in Moscow with the Soviet Union, which offered no help whatsoever. The government declared Belgrade an open city, which under the laws of war meant that the capital would not be defended. On 3 April Major Vladimir Kren of the Yugoslav air force, a Croat who later headed the air force of the Ustaše state, flew to Graz and gave the Germans the locations of the auxiliary airfields, the air force codes and, according to some sources, the layout of the air-raid shelters in the capital. The German embassy left Belgrade, warning allied missions to do the same. On the afternoon of 5 April a British officer warned the leader of the coup, General Borivoje Mirković, that the capital would be attacked the next day at 6.30.

The opposing forces

Against Yugoslavia the Germans fielded more than a dozen divisions in all, including five panzer divisions, with over 330,000 men and some 875 tanks. In the north, in Styria, Carinthia and south-western Hungary, Colonel General Maximilian von Weichs’s 2nd Army was assembling, with XLVI Panzer Corps, LI Army Corps and XLIX Mountain Corps. In the east, in Bulgaria, stood List’s 12th Army, whose XL Panzer Corps under General Georg Stumme was to strike at Skopje, while Colonel General Ewald von Kleist’s 1st Panzer Group, subordinated to it, was to advance on Niš and Belgrade. From western Romania, from the area of Timișoara, General Georg-Hans Reinhardt’s XLI Panzer Corps, with the SS division Reich and the Großdeutschland regiment, was to move on the capital. The campaign was directed personally by the Commander-in-Chief of the Army, Walther von Brauchitsch, who moved to Wiener Neustadt on 5 April. It was supported from the air by General Alexander Löhr’s Luftflotte 4, including Wolfram von Richthofen’s VIII Air Corps – more than 800 aircraft over Yugoslavia alone. The Italians prepared General Vittorio Ambrosio’s 2nd Army in Venezia Giulia and Istria, and part of the 9th Army in northern Albania, some 22 divisions in all. The Hungarians readied their 3rd Army.

On paper the Royal Yugoslav Army numbered more than a million men in 28 infantry and 3 cavalry divisions, but it was an army of the previous war. Most of its artillery was horse-drawn, it had only a few dozen modern tanks, anti-tank and anti-aircraft weapons were in short supply, and a third of the conscripts lacked even uniforms. The air force had more than 400 combat aircraft, including modern Messerschmitt Bf 109s, Hurricanes and domestically built Rogožarski IK-3 fighters, but only just over a hundred modern fighters. Mobilisation was still under way, and according to a post-war American study based on German documents only eleven divisions were in their assigned positions when the attack came. War plan R-41 called for the defence of the entire frontier, more than three thousand kilometres long, including in the north, in Slovenia and Croatia, and in the event of defeat a withdrawal southwards to link up through Albania with the Greeks and the British, as on the Salonika front in 1918. The historian Jozo Tomasevich believed that this plan doomed the army to defeat from the outset, because it dispersed its forces in a cordon without reserves. Abandoning the Croatian and Slovene lands without a fight, however, was politically unacceptable to the government in Belgrade.

Operation Strafgericht

The first wave arrived over Belgrade between 6.30 and 7.00. According to the most frequently cited figures, it consisted of several dozen Ju 87 dive-bombers and more than 150 He 111 and Do 17 bombers, escorted by Messerschmitt Bf 110s and Bf 109s from airfields in Austria and Romania. The bombs fell at intervals of a quarter of an hour or so for almost an hour and a half. They hit the power station, the main post office and the central telegraph office, the Ministry of the Army and Navy, the General Staff building, the military academy, the royal palace at Dedinje, the Guards barracks and the airfield at Zemun, but also residential districts in the centre. At around 10.00 a second wave arrived, at 14.00 a third, from Vienna, and at around 16.00 a fourth. The raids were repeated on 7 April. Löhr’s order of 31 March spoke of “destroying Belgrade by a major air attack”, although according to some historians he assigned his airmen specific military targets at the last moment. To justify the attack on a defenceless open city, German propaganda called it “Fortress Belgrade”.

The defence was powerless. Yugoslav fighters from Zemun and the surrounding airfields took off against every wave and fought with great determination, but they could not stop several hundred aircraft. According to figures compiled by aviation historians, on the first day the Yugoslavs lost ten fighters in the air, with fifteen more damaged, and the Germans twelve aircraft. The anti-aircraft guns in the city were silenced during the first wave, and later Stukas dived almost to rooftop height. The minister of construction, the Slovene Catholic politician Fran Kulovec, was killed in the ruins. Incendiary bombs destroyed the National Library of Serbia: hundreds of thousands of books, maps and medieval manuscripts went up in flames. The zoo was hit, and terrified animals wandered among the rubble. According to a report by Luftwaffe engineers drawn up after the city was occupied, 20–25 per cent of Belgrade’s area was destroyed, and the historian Stevan Pavlowitch wrote that almost half the dwellings were destroyed or damaged. Depending on the source, between more than two hundred and more than three hundred and sixty tons of bombs fell on the city.

The number of dead is still disputed, with estimates ranging from around 1,500 to 17,000. There are reasons for this spread. The highest figure, “more than 17,000”, was given by an American military study of 1953 that relied on early, unverified accounts. The occupation authorities announced 2,271 dead soon after the raid. Other sources, especially post-war Yugoslav ones, speak of 5,000–10,000 victims or more. Tomasevich, drawing on careful post-war research, considered 3,000–4,000 the most realistic figure. Today the most commonly cited figure is several thousand dead, the overwhelming majority of them civilians.

The raid achieved the aim the Germans had set for it. It severed communications between the high command and the armies in the field and paralysed the state in the first, most crucial hours of the war. King Peter II, the government and the high command left the capital immediately after the first wave and moved inland. Simović, who was to have given away his daughter in marriage that day, thereafter directed the war over makeshift lines, and his orders reached the troops late or not at all. Belgrade joined the list of cities the Luftwaffe had bombed to break an enemy’s will: Guernica, Warsaw and Rotterdam. Löhr, who had also commanded the raids on Warsaw, was sentenced after the war by a Yugoslav court, among other things for the bombing of Belgrade, and executed in 1947. In retaliation, RAF Wellington bombers from airfields in Greece bombed Sofia on the nights of 6–7 and 12–13 April, although Britain was not yet at war with Bulgaria.

The thrust from Bulgaria

On the ground the decisive blow fell in the south. At dawn on 6 April the XL Panzer Corps set off west from the Kyustendil area, across the mountains into the Vardar valley. The 9th Panzer Division broke through the defences of the frontier guards and Yugoslav divisions on the road through Kriva Palanka, while the 73rd Infantry Division advanced further south, through Štip. Further south still, the 2nd Panzer Division pushed through Strumica into the rear of the Greeks defending the Metaxas Line. On 7 April German tanks took Kumanovo and Skopje, and the infantry Veles. Within two days the Germans had cut the Morava–Vardar valley and with it the route by which, according to plan, the Yugoslav army was to withdraw to Greece. Prilep fell on 8 April, and on 9 April the motorised SS brigade Leibstandarte Adolf Hitler took Bitola and set off for Florina in Greece. The plan for a new Salonika front had collapsed before it could even be put into effect.

On schedule, at dawn on 8 April, Kleist’s 1st Panzer Group attacked from near Sofia. General Gustav von Wietersheim’s XIV Panzer Corps, led by the 11th Panzer Division, crossed the border near Pirot and, despite bad weather, roadblocks and stubborn resistance by the Yugoslav 5th Army, broke through its positions that same day. On the morning of 9 April German tanks drove into Niš and set off north along the Morava valley towards Belgrade. Meanwhile the Yugoslav 3rd Army, in accordance with the plan, attacked the Italians in northern Albania on 7 April and for several days advanced towards Shkodër. This was the only sector on which the Yugoslavs went on the offensive, but the Germans soon appeared in the rear of these troops, in Kosovo and Macedonia, and the offensive had to be broken off.

Bridgeheads on the Drava

In the north, Weichs’s 2nd Army was still assembling when war broke out. Some of its divisions were detraining and were not due to move until 10 April. On 6 April, however, its first-echelon units carried out limited-objective attacks. LI Corps captured intact bridges over the Mur at Mureck and Radkersburg and took Murska Sobota, while units made up of instructors and recruits seized bunkers and passes on the border of Carinthia and Styria. On the evening of 6 April, in view of the weak resistance, the XLVI Panzer Corps was ordered to seize bridgeheads on the Mur and the Drava, among other places near Barcs in Hungary. On the evening of 8 April a German detachment under Captain Palten took Maribor without a fight, though against orders and only briefly.

The 2nd Army’s offensive got under way in full strength on 10 April. That day the tanks of the 14th Panzer Division covered some 160 kilometres from the Drava bridgehead and at 7.30 p.m. stood on the outskirts of Zagreb, where the Independent State of Croatia had been proclaimed a few hours earlier. According to the American military study, on the way to the city they took more than 15,000 soldiers prisoner, including 22 generals, among them the commanders of the 1st Army Group and the 7th Army. The 8th Panzer Division set off east between the Drava and the Sava towards Belgrade. On 11 April the Italians went over to the attack, quickly occupying Slovenia and advancing along the Dalmatian coast, as did the Hungarians, who entered Bačka and Baranya without meeting serious resistance. Romania did not take part in the invasion, although its artillery fired on Yugoslav barges on the Danube, and Bulgaria, from whose territory the German thrust had been launched, moved into Macedonia only after the Yugoslav capitulation.

An army that fell apart

The Germans had expected a hard campaign in the mountains. Instead, Yugoslav resistance collapsed faster than anyone had imagined. The reasons were various. The army was poorly armed, not mobilised and strung out along the frontiers, and after the bombing of Belgrade it was leaderless. Of the 165 generals on active service, all but four were Serbs, and many soldiers of other nationalities saw no reason to die for a state in which they felt themselves to be second-class citizens. The best-known example was the mutiny in the Bjelovar area on the night of 7–8 April, when Croatian soldiers of the 108th Infantry Regiment disarmed their Serbian officers, took over command and then occupied the town. On the Drava, Croats of the 4th Army refused to fight in several places, threw away their weapons or went home. The leader of the Croatian Peasant Party and deputy prime minister, Vladko Maček, who had joined Simović’s government only on 3 April, left the government in the first days of the war and remained in Zagreb. Ustaše agents and part of the German minority were also active, and the Germans skilfully fanned these divisions with propaganda.

Historians disagree about how great a role these mutinies played. After the war Serbian nationalists blamed the defeat on a Croatian “fifth column”, while Croatian nationalists blamed the Belgrade politicians and the Serbian officer corps. Tomasevich and other scholars pointed out that the main causes lay in the army itself: in its obsolete weapons, its poor defence plan, its unfinished mobilisation and the weakness of its command. The historian Aleksa Đilas drew attention to the fact that many Croatian units did fight the Germans and that most Croatian officers remained loyal until 10 April, when the proclamation of the Croatian state robbed that loyalty of its meaning. The fighting, on the other hand, was done above all by Serbian units, although they too, taken by surprise and cut off from communications, were destroyed one after another. On 11 April Simović sent the army an appeal to fight the enemy wherever they met him, without waiting for orders from above. It was in effect a signal that the high command had ceased to command.

Place in the war

The Yugoslav campaign was shorter than anyone had expected. On the evening of 12 April a small SS patrol accepted the surrender of Belgrade; on 15 April the Germans took Sarajevo, and on 17 April representatives of the Yugoslav high command signed the unconditional surrender of the army in Belgrade. According to the American study based on German documents, the Wehrmacht lost 151 killed, 392 wounded and 15 missing in the campaign, and the Luftwaffe some sixty aircraft. The King and government fled abroad and carried on the war in exile. The state was divided up between Germany, Italy, Hungary and Bulgaria, and in Croatia and Bosnia power was seized by Ante Pavelić’s Ustaše, who began a genocide of Serbs, Jews and Roma. In the summer of 1941 uprisings broke out in Serbia and Montenegro, and with them a partisan war, a civil war and German reprisals that lasted until 1945 and claimed, by various estimates, around a million lives.

The swift victory allowed the Germans, together with the conquest of Greece, to take control of the entire Balkans in April, securing Romanian oil and the southern flank before the attack on the Soviet Union. Hitler postponed the start of Operation Barbarossa, and historians still argue about the extent to which the Balkan campaign contributed to the delay. The troops that crushed Yugoslavia in April 1941, however, had to head north again within a few weeks, leaving weak occupation divisions behind in the country. It was in this gap that one of the largest resistance movements of occupied Europe was born.