The first shots of the Great War did not explode from a battleship on the high seas. They came from a relatively small, river monitor in the darkness, Seiner Majestät Schiff, (his majesty's ship) SMS Bodrog, firing shells across the Sava River toward Belgrade just after 1:00 AM on July 29, 1914. The most devastating war in human history opened not with a charge across the field, but with action in a tight river bend.
The Bodrog's bombardment was more than Austria-Hungary's opening salvo against Serbia. It reveals how geography drives strategy and how navies fight in three distinct theaters of water—blue, green, and brown. In the Balkans, the Great War began in the brown water. Understanding this fact clarifies not only Austria-Hungary's opening gambit, but the stubborn, river-bound character of those first crucial days of struggle in the Balkans and which revealed just how unprepared the Imperial and Royal forces of the Habsburgs were for combat.
Like armies, ships and fleets are tailored for purpose. When they say "Blue water fleet" it means deep-ocean fleets operating globally—aircraft carriers, cruisers, destroyers with the range and endurance for extended operations. These are the ships that project power across continents and control the sea lanes. Green water covers the coastal and near-offshore zones, straits, island chains, the littorals, where sea power reaches inland and land power stretches toward the sea. Here where you often find hotly contested zones, especially when governments attempt to stop smuggling and other ship-bound criminal activity. It is also cheaper for a small and medium sized country to build and maintain a green water squadron. And then Brown water encompasses the interior zones bounded by land on either side. Rivers, canals, and other shallow coastal areas are the domain of shallow-draft gunboats, monitors, and patrol craft. These vessels carry modest guns but offer something that in the right hands could be decisive in riverine warfare: persistent, mobile firepower where roads are scarce, bridges are unreliable, and the front line curves around the bend. Americans became adept at these operations in Vietnam's Mekong Delta.
Today, the Sava River is a river in the western Balkans with a basin covering much of Slovenia, Croatia, Bosnia, and northern Serbia. These days the Sava rises in Slovenia's Julian Alps (Julijske Alpe), then curves past Ljubljana - the capital of Slovenia - and Zagreb, marking the boundary between Croatia and Bosnia, and meets the mighty Danube at Belgrade, the capital of Serbia. The Sava’s tributaries are the Savinja, Krka, Kupa, Lonja, Una, Vrbas, Bosna, Drina, and Kolubara rivers. Major towns and cities along the river are Kranj, Zagreb the capital of Croatia, Sisak, Slavonski Brod, Bosanski Šamac, Sremska Mitrovica, and Šabac. And the Sava itself is a tributary of the Danube that forms a northern boundary of Croatia. Finally, the Drina flows north, forms part of the eastern boundary with Serbia, and is also a tributary of the Sava. That bit of trivia is important because in 1914, it was the critical frontier between the Austro-Hungarian Empire and the Kingdom of Serbia: the town of Zemun on the Austrian bank, the Serbian royal capital of Belgrade looming from the other. In the Balkans peril lurks in mountains, valleys, wrong turns and rivers bends. Especially for invading armies.
On July 28, Vienna declared war. Hours later, the Bodrog and the Danube Flotilla opened fire. The SMS Bodrog was named for a Hungarian river, befitting the ship's purpose and it was this little ship which was only 440 tonnes, and not the 18,000 tonnes of a dreadnought that kicked off the Great War. In 1914, the treacherous Balkan geography demanded speed from Austria. Speed before the Russians could pounce if they decided to help the renegade Serbian regime, which seemed likely. It is odd that Serbia, which had indulged in regicide, should have been the cause the Romanovs of Russia were willing to die for. But back to the issue at hand, since Belgrade sits at the confluence of two major rivers, if Austria-Hungary intended to crush Serbia quickly, it had to contest the river crossings immediately. The Austrian army was still mobilizing and shifting units under General Oskar Potiorek's invasion plan. Potiorek had something to prove, something to make up for really. It was his office that failed to inform Archduke Franz Ferdinand's driver of the new route in Sarajevo, causing him to make the wrong turn that put the crown prince and his wife directly in the assassin's line of fire. Despite the pressure and need to win, his army struggled regardless. As I have written before, Austria-Hungary was the last Catholic great power and had been a comparatively peaceful country. Its army had not fought a major battle in almost fifty-years.
Serbia and its ally, Montenegro mustered around 450,000 men in the first week of August. They had just fought and won the two Balkans Wars of 1912-1913 so they were ready for another fight. Their forces were divided into three armies against Austria's two armies. Austria should have had three armies in the field, but the army high command, Armeeoberkommando, received troubling tidings from the east: they redeployed the other field army because Russia had joined the war. Austria, was now outnumbered even if Germany joined in response to Russia. And after Germany joined, then France too entered the war despite not being threatened. Without France, Russia and Serbia already outnumbered Germany and Austria, and with France, their combined populations outnumbered the Central Powers by nearly 100 million.
The fate of the Habsburg dynasty that had withstood Martin Luther, and in whose name Hernán Cortés conquered the Aztecs, and for 500 hundred years had been the most stalwart defenders of the Catholic cause, came down to smashing Serbia quickly, before the weight of Russia fell on the eastern frontiers. Potiorek failed. Not because of the Sava however. Crossing the Sava from the North was the direct way to Belgrade. Austria knew that, and Austrian high command knew the Serbians knew they knew that. So they came from another direction. The Serbs did not expect it, and still, Potiorek failed. Now the forces of the Dual Monarchy had to hope their German ally could save them from the Russian onslaught. Potiorek would continue to battle the Serbians until just before Christmas. But why did the plan fail on ground Austria chose?
