To Arms

by Hew Strachan

  The danger was that the Serbs would not be drawn in to the defence of Belgrade. They might concentrate in the south or, even if they did not, they might fall back to Nis, so prolonging the campaign and extending the Austrians’ lines of communication. During the Bosnian crisis, therefore, Conrad put the weight on the west, planning to support the thrust across the Save with another across the River Drina, and up the course of the Jadar to Valjevo. Between 1909 and 1914 this drift from north to west intensified. If the Serbs attacked the empire their most likely line of advance was into Bosnia-Herzogovina. Conrad stressed the difficulties of crossing the Danube, and removed from the command of the 5th army those (including Krauss) who disagreed with him. Potiorek, who had at first favoured the attack on Belgrade, went even further than Conrad. As commander of the 6th army, his responsibility was for the defence and security of Bosnia. He was anxious to encounter the Serbs as far east of Sarajevo as possible. He therefore planned to advance directly on Uzice, via Visegrad and crossing the upper Drina. The area was mountainous, it lacked road or rail communications, and a war game conducted in April 1914 revealed that independent attacks on the upper and lower Drina would be too far removed from each other to have reciprocal effects. The 6th army’s advance would therefore be slow, hampered—in all probability— by unrest to its rear, as well as by stubborn Serb defence to its front.

  The immediate strategic purpose of the offensive from the west was defence. It failed to meet any of the required political objectives of 1914. Vienna could not ‘halt at Belgrade’ as the Kaiser requested because it had no plan for such an operation; nor could the army deliver the quick victory the diplomats wanted in order to shore up the empire’s position in the Balkans. The offensive’s wider military purpose was to cut the Serbs’ line of retreat from the south. But the Austrians could not be sure of having accomplished this objective until they had crossed the width of Serbia and reached Nis. In the interim the Serb army would need to be held in the north, not left free to manoeuvre. Thus, in practice the western offensive could not proceed without some form of attack in the north, and vice versa. Operational demands meant that the success of a thrust along any one axis would depend on some activity along the others.110

  MAP 11. SERBIA

  Accordingly, the plan for war with Serbia finalized in November 1913 contained both elements. The 5th and 6th armies would cross the lower and upper Drina respectively, the 2nd army would attack on the Save, and a reinforced corps, the ‘Gruppe Banat’, would traverse the Danube east of Belgrade and push up the Morava valley. Throughout the July crisis Potiorek developed this plan, assuming that the Balkans would be the principal theatre of operations and that he would have full use of the 2nd army in its implementation. The decision to switch the 2nd army to Galicia ought, in terms of strict military logic, to have resulted in a move from offence to defence. The strength of the Austrian forces in the theatre was clipped from 370,000 men to a maximum of 290,000, including a large proportion of garrison troops; the Serbs swelled to 350,000 as they incorporated their reservists.111 Potiorek was told that his minimum task was to prevent a Serb invasion of Austria-Hungary. But the maximum was not specified. Operationally, Conrad’s acceptance of the offensive orthodoxy meant that he would not oppose an attack; diplomatically, Berchtold remained desperate for a Balkan victory. Potiorek was nothing loath. His administrative responsibilities in Bosnia-Herzogovina and the constant threat of Serb irridentism swelled him in his conviction that attack was the best form of defence and that the approach across the upper Drina should be the main avenue for such an operation. The fact that the 2nd army was only temporarily available confirmed him in his wisdom. It meant that he should act now while he still had the manpower advantage, and it confirmed that the main thrust would have to come from the west and not from the north.

  On 6 August AOK gave Potiorek the use of the 2nd army until 18 August, when it would begin its move to Galicia; it was not to cross the Danube or the Save. Potiorek decided to centre his operations on the efforts of the 6th army, although lack of transport meant that it would not be able to concentrate near Sarajevo before 13 August. It would then have to march for five days before it could deploy on the River Drina. The pressure on the Serbs to the north would be lifted as that to the south began to take effect. The logical conclusion would have been to leave the 2nd army on the Serb frontier and to move the 5th, the army due to mount the thrust from the north-west along the Jadar river towards Valjevo, to Galicia. The fact that this option was not considered was not simply because there were too few railway lines to effect a switch sufficiently rapidly; it was also the product of the differing conceptions of Serbian operations entertained by Potiorek and Conrad. Potiorek saw the task of the 5th army as support for the movements of the 6th. The terrain which confronted it was less mountainous, and he wanted the 5th to push on Valjevo as fast as possible, weakening the flank of any Serb thrust from Uzice to Sarajevo, while itself inclining to the right so as to ease the path of the 6th. The Serbs would be drawn onto the 5th army and then hit in the flank by the 6th. Conrad attached less importance to the 6th army. For him, the major offensive was to be mounted by the 5th, the focus therefore lay along the Save and the Danube, and the 2nd army could thus provide real diversionary aid to facilitate the 5th’s opening moves. Potiorek protested that the 5th army was untrained for warfare in the mountains. He harked back to the plan concerted by Beck in 1882 and still preferred by Conrad in 1909, to encircle Serbia’s army in its north-west corner, between the Save and the lower Drina. Massive envelopment would become impossible if the 5th army’s offensive proved successful in fulfilling Conrad’s aim, ‘to defeat the enemy and to prevent him breaking into the empire through a thrust into his heartland’.112

  Both plans egged on the 5th army and minimized the obstacles in its path. Conrad wanted it to exploit the availability of the 2nd army, and so was more concerned to achieve reciprocal action on the 5th’s left than he was worried by the six days’ gap between the attacks of the 5th and 6th armies on the right. Potiorek did not object because this separation in time was exactly what he hoped to achieve. He believed that the Serbs had only light forces on the lower Drina. Accumulating indications that this might not be true did no more than serve the hopes of both commanders that Serbia’s forces would be pulled into its north-west corner and enveloped.

  Conrad’s growing respect for the Serbian army before the war had much justification. It had transformed itself from a poorly trained militia, relying on a spontaneous peasant uprising, into a modern conscript force, possessed of a professional officer corps and a body of trained reserves. All men aged between 20 and 27 were called up for two years’ regular service. On reaching the age of 31 soldiers transferred first to a second and then to a third levy, finally completing their military liability when they were 50. Therefore, the first-levy strength of 180,000 men rose on mobilization to 350,000. Between 1898 and 1901 the closure of half the gymnasiums in Serbia and the increased availability of scholarships to the military academy had attracted to the army the bright and the ambitious. The officer corps saw itself as democratic, nationalist, and professional. In 1912 the army had mobilized ten infantry divisions and one cavalry division, and had beaten first the Turks and second, in 1913, the Bulgarians. Thus, unlike the Austro-Hungarians, the Serbs had recent battle experience. They had learnt the value of heavy artillery and the importance of entrenchment. The experience of guerrilla operations in Macedonia against the Turks had modified the formal tactics of European models.113

  But the Balkan wars had also weakened the Serb army. The newly acquired territories had not been fully assimilated for military purposes, and parts were in near revolt. Total losses may have risen as high as 91,000. More serious for a country of such economic backwardness was the loss of equipment and the expenditure of ammunition. On 31 May 1914 the minister of war, having embarked on a ten-year programme to rebuild the army, declared that Serbia was not yet fit to fight.114 The rifles in use were of a va
riety of types (ironically, the best and most widely used, Mausers, had been supplied by Germany), and there were only enough modern patterns for the peacetime complement of 180,000. In some units up to 30 per cent of infantrymen had no rifles at all. There was less than one machine-gun for each infantry battalion. The Serbs had acquired 272 75 mm field guns from the French, and had better field howitzers than the Austrians. But after they had given 100 guns to Montenegro, their total complement of field guns was 528, of which only 381 were quick-firers. Each first levy division had twenty to twenty-four guns as well as up to twelve howitzers, and each second levy division had half that, many of them not horsed. The recent fighting had depleted shell stocks. Serbia itself could produce 250 to 260 shells per day, but only enough powder for eighty to 100. It had about 700 rounds per gun in stock, and looked to France and Russia to make up the deficit.115 The Serbs’ reliance on the Entente powers for equipment created a dependence that robbed them of strategic freedom, and a vulnerability which their land-locked isolation did nothing to mitigate. The Russians sent 150,000 rifles, the French sent artillery; in exchange, both powers demanded that the Serbs attack.

  The bulk of the Serbian army on the war’s outbreak was concentrated in Macedonia, in anticipation of war with Bulgaria. This threat to the east could never be totally discounted. Furthermore, the value of the ally to the west, Montenegro, was limited. The 35,000 men of its national militia had only sixty-five guns and thirty machine-guns; it possessed no real headquarters, and there were no plans for joint operations with the Serbs. The nominal commander-in-chief of the Serb army was Crown Prince Alexander, whose reputation (and political ambition) had been reinforced by the success of the Balkan wars. But the real direction of war rested with the chief of staff, Radomir Putnik. Putnik, the son of a teacher, a gunner and former lecturer at the military academy, had stood at the apex of the Serbian army since 1903—as chief of the general staff for most of the time, and minister of war for the rest. He was 67 and he was suffering from emphysema, but he had two great strengths: he commanded the respect of the competing political groups in Serbia, and he was thoroughly familiar with the plans for his country’s defence.

  Putnik’s return from taking the waters at Gleichenberg was followed by a bout of pneumonia. He did not, therefore, arrive at his headquarters until 5 August. Extraordinarily, he had taken with him the keys to the safe in which Serbia’s war plans were locked, and his staff had to blow it open before they could begin the process of mobilization and concentration.116 The Serbs had expected their mobilization to be slow—not because of this haphazard start to the war but because the railway lines for moving their forces from south to north were inadequate. The country was divided into five divisional regions, each being responsible for raising one first levy division and one second levy. But the result of Serbia’s enlargement and of the problems in the south was that seventeen infantry regiments were outside their mobilization areas. Furthermore, the deplacement to the south meant that, whereas in 1912 half the army had been able to march to the front, in 1914 only 30 per cent could do so. The rest had to go by train. Of the 2,023 carriages required, 1,597 were available. The deployment plan had been drawn up in 1908, and it may subsequently have been updated in the light of information derived from Colonel Redl and passed on by the Russians.117 Its preparation had been ordered on 11 July. The Serbs, as the Austrians appreciated, had at least had plenty of practice in the drills of mobilization. Furthermore, Putnik had an able deputy in the shape of Zivojin Misic. By 10 August the Serbs’ concentration was complete.

  Putnik’s preferred modus operandi was offensive defence: he deployed defensively and in depth, but only as a preliminary to the counter-attack. He reckoned that, on balance, the Austrians would attack from the north. However, he concentrated his three armies in such a way that they could, if necessary, face a threat from the west. They were placed in a central position in north Serbia, along the east-west railway line from Palanka to Valjevo. A separate group in Uzice guarded their rear from an attack and linked with the Montenegrins. The 2nd Serb army was reinforced and given the principal operational task—either to counter-attack against the right flank of an invasion from the north or the left flank of one from the west. The 3rd army, on the 2nd’s left, was poised to counter any thrust from the Drina-Save triangle. Frontier guards had the task of identifying the main direction of the enemy’s attack.

  Potiorek began his advance on 12 August. His forces had not had time to complete their concentration, their supply services in particular still struggling to catch up. The 5th army lacked sufficient bridging equipment, and its commander had wanted to postpone the attack for two days. The Drina was a formidable obstacle—broad, deep, fast-flowing, with steep, wooded banks. The 5th army did not get across until 15 August. AOK allowed the 2nd army to establish bridgeheads at Mitrovica and Sabac. By the 14th Putnik had concluded that the 5th Austro-Hungarian army’s thrust on Valjevo was the main attack, and the 2nd’s on Sabac was secondary. He began warily—for he was still anxious about the position in the north—to move his armies westward, with the 2nd army to the north, the 3rd in the centre, and the 1st to the south. On 15 August the 5th Austro-Hungarian army, supported on its left by elements of the 2nd, ran into the 2nd and 3rd Serb armies on a front shielded by the Dobrava and Jadar rivers. The Austrians, sniped at by guerrillas, toiled uphill in soaring temperatures. They had outstripped their supplies and they were not equipped for mountain warfare. Frank, the 5th army’s commander, was preoccupied with the threat of envelopment by the 2nd Serbian army on his left; Potiorek continued to stress the right. The latter’s orders on 16 August treated the Serbs as beaten troops and set distant objectives on the Kolubara river. But Putnik, focusing on the centre rather than on the flanks, fought a stubborn battle on the Cer plateau. With the 2nd Serb army holding to its front, the 3rd Serb army was able to restore the situation on Putnik’s left. Potiorek now shifted his attention to the Austrian left. But it was stuck at the Sabac bridgehead.

  On the Austro-Hungarian left Potiorek demanded to be allowed to commit all the 2nd army against the Serb right. Conrad, however, was anxious to move the 2nd army to Galicia on 18 August as planned, and would only agree to the temporary release of one corps to the 5th army. This, Tersztyansky’s IV corps, attacked on 19 August, but then, just as the 2nd Serb army was about to give way, broke off on the orders of AOK. VIII corps of the 5th army, elements of which had been hit hard in a Serb attack on the Cer plateau on the night of 16 August, was ordered to withdraw across the Drina; at least one division had lost a third of its rifle strength. By 20 August the 5th army’s other corps, XIII, was unsupported: Frank told IV corps to fall back across the Save, an order reiterated by AOK. But Potiorek instructed IV corps to hold the Sabac bridgehead, so as to enable the 5th army to stay east of the Drina. The Austrians were shaken by the ferocity of the Serb attacks and by the way in which the entire population rallied to the country’s defence. The 2nd army began its move to Galicia on 20 August, although IV corps stayed behind until the 24th as it continued to hold the Sabac bridgehead. The 2nd army had been denied a decisive role in Serbia. It could have achieved a major success at Sabac only if it had put its entire strength across the Save. Furthermore, by acting so close to the 5th army, it failed to mount any major threat along the Danube, opposite Belgrade. Thus, Putnik was able to leave weak forces in the north and east and concentrate to the west.

  In practice, therefore, the 6th army had to support the 5th army, not vice versa as Potiorek had planned. Under Potiorek’s personal command it completed its approach and deployment on schedule. On 20 and 21 August it won local successes at Visegrad and Priboj. But their effect was too late and too distant from the main battlefield. The Serbs were able to fight a series of separate battles on interior lines. The 6th army fell back. Potiorek had failed to combine in time or space, Putnik had not.118

  With its own territory clear, at least for the moment, Serbia began to pay the price of its dependence on i
ts allies. Russia, which had entered the war in Serbia’s defence, now demanded that Serbia launch an attack into Austria-Hungary in order to draw Austrian troops away from Galicia and so support the South-West Front’s advance. Potiorek’s offensive suggested that there were few Austro-Hungarian forces to the north and that Herzogovina and southeast Bosnia were only weakly held. On 6 September the 1st Serb army crossed the Save in the direction of Srem, just north of Belgrade, while the 2nd army launched a feint against Mitrovica to the left. The remainder of the 2nd and all the 3rd army faced the Austrian 5th and 6th armies on the Drina. To the south, the Uzice group and the Montenegrins moved behind the 6th Austrian army, towards Sarajevo, hoping to trigger a popular rising in Bosnia.

  Potiorek attributed his first defeat to the interventions of AOK and the loss of the 2nd army, rather than to his own failings. He began immediately, on 24 August, to plan a second attack, and AOK, sensitive to the possibility of Serb offensive, approved its commencement on 3 or 4 September. But Frank dragged his feet: the 5th army had lost more than a quarter of its strength of 80,000 men, and needed to re-equip and re-form. Potiorek, therefore, brought the 6th army further north, to the middle Drina, so closing the gap with the 5th army. Rain postponed his attack, and then came news of the Serbs’ advance across the Save. XV corps, the formation linking the 6th army’s left to the 5th’s right, was not yet ready, but Potiorek ordered the reluctant Frank to attack, together with XVI corps from the 6th army’s right. The 5th army’s attack on 8 September, unsupported by artillery and with its pontoons swirling in the river, failed. But to the south XVI corps, striking north-east across the front of XV corps and to the south of Loznica, got across the middle Drina with light losses and hit the flank of the 3rd Serb army. The Serbs had to bring elements of the Uzice group up to support their 3rd army, so weakening their advance on Visegrad. The Serb invasion of Bosnia failed to produce any popular response, despite the use of bands of guerrillas dubbed Cetniks, and the Serbs and Montenegrins fell out.