In October of 1938, Air Force General Dusan Simovic, as armed forces Chief of General Staff, drew up Plan S in response to the German annexation of Austria. This plan assumed a German-Italian offensive that would include a thrust across Yugoslavia's western frontier from Hungarian territory.

To counter the expected attacks, construction of a series of border fortifications was ordered along Yugoslavia's northern borders with these three countries. At the time of the actual invasion, however, they were only forty per cent completed, consisting of only light machine guns, embrasure stands, wire obstacles, and anti-tank ditches, supported by a minimal number of fixed artillery positions.

In January, 1940, General Simovic was replaced by General Petar Kosic, who in turn drew up Plan R-40, which took into account the Italian conquest of Albania. This plan called for a swift elimination of the Italian enclave at Zara, a slow fighting withdrawal of the troops along the northern border, and a purely defensive holding action along the Albanian frontier. Plan R-40, too, was soon made obsolete by the German Army's entry into Rumania, the Italian action against Greece, and the probability that Bulgaria would join the Axis cause.

Plan R41 was drawn up as a modification of the previous plan. R41 called for a combined offensive with the Greek Army to drive the Italians out of Albania, a holding action on the Bulgarian front, and a defense in depth along the other borders. The first line was the border fortifications within a mile or so of the frontiers, intended to delay the invasion long enough for the army to blow the bridges, issue mobilization orders, and form up its operational armies behind the primary line of resistance.

The primary line, behind the Drava, Danube, and Nisava Rivers, was intended to stop the enemy for at least three weeks, during which time the reserves could be mobilized and preparations made for defense behind the main line of resistance. The main defense line was in the Bosnian and West Serbian highlands behind the Sava and Morava River line. This defense line was considered strong enough to hold out for months, during which time either an alliance could be activated to enable Yugoslavia to counter-attack, or a decision could be made to withdraw southward toward Salonika and the Allied positions in Greece.

The Yugoslav defense was formulated around one significant false assumption: that a united Yugoslavian Army would rise to the defense of the nation. In fact, however, three of the nation's minorities the Croats, Magyars, and Germans defected to the invaders. They gave the Axis troops intelligence information and surrendered to the Germans whenever they could. Some Croatian units rebelled, attacking their own headquarters positions, holding vital bridges until the German columns could reach them, or bringing boats to the invading troops to aid in river crossings.

Even without the wholesale defections and political desertions, the defensive plan had not been adhered to, and this was one of the primary factors which enabled the German and Axis forces to bring such a swift and complete defeat upon the nation.

Yugoslavia had been invaded on April 6, and yet a vital bridge which penetrated both the initial and primary defense lines was allowed to fall intact into German hands at Zakany on April 7. To compound an unfortunate dereliction, the next day the even more important road bridge at Barcs fell to a German "surprise" attack. According to the defensive strategy adopted by the Yugoslavs, both of those bridges should have been destroyed on the morning of April 6.

Even after the initial border crossings, the bridges across the Nisava and Morava Rivers at Nis fell intact to the 1st Panzer Group. The value of the destruction of the bridges was amply demonstrated when the northern Drava bridges were destroyed, holding the 2nd Army in check for several days. If the destruction of the bridges could have been coupled with a serious resistance effort, von Weichs' command might well have been held up indef initely.

It was not only the bridges which could have been defended, but also the major highway routes. These roads could have been extensively mined, which would have had tremendous effect on the German Army, as it was largely dependent upon vehicular transportation.

This was especially evident in the route of the 1st Panzer Group, where the advance and supply columns were tied to a single road due to rain and the poor conditions of the Balkan road net. It was only in the Sturmitza Valley that the roads were mined, which achieved significant results by turning back one column of the 2nd Panzer Division.

Another very grave error committed by the Yugoslavians was that, because the country was dominated by the Serbians, all of the national leaders, military staffs, major communications networks, and decision makers were concentrated in and around Belgrade. This fact made the bombing of Belgrade throughout the first stage of the campaign essential to the German plan.

The confusion and disruption caused by the Luftwaffe's bombs were felt thoughout the entire country. As it became evident that no leadership was forthcoming from the capital, dissention and rebellion spread among the restive minorities.

Even the German military was surprised by the ease and swiftness of the campaign. Their plans had called for an additional seven divisions to participate, most of which had not yet arrived in the combat theater of operations before the campaign had ended. Thus, the Yugoslavian defeat must not be attributed solely to the overwhelming force of the German mechanized assault. Rather, a lack of willingness to resist on the part of the Yugoslavs themselves must receive at least part of the blame for the swiftness of this blitzkrieg campaign.

Following the March 27 military coup led by General Simovic, the new Yugoslavian government issued general mobililization orders on March 28, 1941. Upon complete mobilization, the Yugoslav Army would have 1,200,000 men in the active army units, with a further 500,000 men assigned to the reserve and border units.

The Yugoslavian military system varied slightly from the standard western military system. After an initial basic training period, the recruit was posted directly to one of the divisions raised from the same recruiting area. Once posted to the division, he was assigned to the division's depot regiment. The Yugoslavian depot formations served the purpose of training manpower to replace any losses which the division might take in combat. In wartime, the depot formations, rather than remaining in rear area garrisons, accompanied the division into combat and were even assigned to limited combat duties.

As units required replacements, trained personnel were transferred from depot units into active commands. The soldier then served in the active units until age of 40, at which time most soldiers were re-assigned into Border Guard, Border Defense, and Reserve Army units.

More Yugoslav Army of WWII

Introduction
Infantry and Border Units
Cavalry and Artillery
Mechanized Units and AA
Navy
Air Force (with OOB)
Army OOB
Yugoslavia Map (slow: 75K)