Serbs cross the Sava and begin the operation in Syrmia

On 6 September 1914 Serbian troops crossed the Sava and entered Syrmia, the region north of the river that then belonged to Austria-Hungary. After the victory on Mount Cer, Serbia carried the war onto enemy territory. The operation, however, began with the defeat of one of the Serbian divisions.

Allied pressure

After driving the Austrians out of the country in August, the Serbian command was in no hurry to go on the offensive. The army was tired and short of artillery ammunition and bridging equipment. Russia and France, however, pressed Belgrade to strike at Austria-Hungary and pin down its troops, which might otherwise be transferred to Galicia against the Russians. Grand Duke Nicholas Nikolaevich, commander-in-chief of the Russian army, wrote to the heir to the throne, Alexander, on the matter. Prime Minister Nikola Pašić gave way, and the chief of staff, Vojvoda Radomir Putnik, prepared a limited offensive.

The main blow was to be delivered by the First Army of General Petar Bojović, which was crossing the Sava in the area of Kupinovo, west of Belgrade. Further west, near Mitrovica, the Timok Division (first levy) of General Stepa Stepanović’s Second Army was to make a feint crossing to draw the Austrians’ attention away from the main axis.

Defeat at Mitrovica

The Timok Division’s crossing went badly from the start. Tired after a night march, the soldiers began crossing near Čevrntija, a few kilometres from Mitrovica, only towards morning on 6 September, and the pontoon bridge had not been completed. The divisional commander led his regiments in between two Austro-Hungarian garrisons instead of taking one of them. The Austro-Hungarians, stronger than the Serbs had assumed and quickly reinforced, counter-attacked on 6 and 7 September around the village of Leget near Sremska Mitrovica and almost surrounded the Serbian units.

The retreat turned into a disaster. The crossing collapsed under the pressure of the fleeing men, many soldiers drowned in the Sava, and most of those left on the far bank were taken prisoner. According to various sources the division lost about 6,000 men, nearly 5,000 of whom were captured. Austro-Hungarian losses are estimated at about 2,000. Serbian historians regard it as their army’s heaviest defeat of 1914. The divisional commander was later court-martialled.

The First Army’s advance

The main forces of the First Army crossed the Sava with greater success and advanced into Syrmia, though cautiously, because after the defeat at Mitrovica their left wing was exposed. By 12 September they had reached the line Novi Banovci – Buđanovci, still far, however, from their objective, the fortress of Petrovaradin on the Danube.

What came next

The expedition into Syrmia was short-lived. On 7 and 8 September Austria-Hungary began the second invasion of Serbia, crossing the Drina. Putnik had to pull his troops back to defend the country, and on 11 September he ordered the withdrawal from Syrmia. By 14 September the last Serbian units had returned behind the Sava. The offensive did not achieve its aim, because some of the Austro-Hungarian troops intended for Galicia had already left for the east, and it cost Serbia several thousand soldiers whom it had no means of replacing.