Serbia, Austria-Hungary’s initial enemy, had no naval forces on the Danube, and the Russians could not bring their trio of fairly powerful gunboats of the Donetz class beyond the lower reaches. They did employ a few improvised craft in Serbian waters below the Iron Gates, the famous and most dangerous of the series of rapids that cut through the southern arm of the Carpathian mountains. Romania had a river force on paper, including four monitors built in Trieste in 1907–8 and armed with three 12-cm Skoda cannon. They could have been troublesome opponents for the k.u.k. Donauflottille, but Romania remained neutral until 1916, and when she entered the war the circumstances of the campaign were such that the rival monitors remained far apart. It is therefore somewhat ironical that in the prewar maneuvers the Austro-Hungarian Danube Flotilla, with the example of the American Civil War before them, tended to practice for a classic battle with enemy monitors on the river just the way the major navies prepared for a classic encounter on the high seas, which, as it turned out, occurred only once at Jutland. The real employment of the Austro-Hungarian navy on the Danube during the war was in cooperation with the army in land operations, particularly artillery support, and this aspect of riverine warfare had been neglected in the prewar maneuvers.2
The Danube Flotilla was split in three when the war began. The major part of it, including four monitors and three patrol boats, was on the Danube at Zemun, just upstream from the Serbian capital Belgrade. The two oldest monitors, the Leitha and Maros, and a patrol boat were on the Save, and two patrol boats were at Pancsova, downstream from Belgrade on the Danube. The Save, which formed the boundary between Serbia and Hungary, flowed into the Danube at Belgrade, and the Serbian batteries in the Kalimegdan fortress, on Topcider Hill to the south, and in other positions around the city, were the natural opponents of the monitors. The two rivers and the islands in them near where they joined at Belgrade were the focal point of operations for over a year. Low water, however, prevented the flotilla from operating on certain reaches of the Save for about a month after the end of August.
The Austrians declared war on Serbia on 28 July. On the night of the 28th, the monitors Temes, Bodrog, and Szamos fired the opening shots of the war against the Serbian fortifications at the Zemun-Belgrade railway bridge over the Save and on Topcider Hill, and after daybreak shelled the wireless station and Serbian positions on the lower portion of the Kalimegdan fortress. The Austrians, however, were caught in a disadvantageous strategic position, for when Russia entered the war, they had to shift forces from their Balkan front to face the far more serious danger in Galicia to the north. The forces left against Serbia were not strong enough to accomplish the mission, and the Austrian offensives against Serbia in 1914 proved to be dismal failures.3 The Serbians were able to counterattack, and on 9 September the Austrians were forced to evacuate the flotilla base at Zemun. The two small patrol boats at Pancsova were cut off and blown up in the Temes River to prevent them from falling into enemy hands. The Austrians were able to recover Zemun, and on 28 September the monitors Temes and Körös, a patrol boat, and the minesweeper Andor were able to break through the minefields in the Save near Belgrade and then move upstream to support the fighting at Sabac.
The monitors had impressed the Serbians, and they did not know how to deal with them. They outgunned the artillery of the Serbian army and as a moving target were difficult to hit. Their mobility enabled them to rapidly bring artillery support to a threatened sector, whereas artillery on land had to be shifted by horses or oxen or manhandled over poor roads and difficult terrain. The Serbians appealed to their allies for support, and the Russians, French, and, eventually, the British responded. This Allied assistance hampered the work of the Austrian monitors and made their operations much more difficult and dangerous.
The Russians were the first to arrive, but any Russian attempt to assist landlocked Serbia ran into geographical difficulties. Serbia had no seaport of her own or any common border with her allies except tiny impoverished Montenegro, whose meager port and road network were totally inadequate. Although the British and French might make use of Montenegrin facilities, such as they were, Turkey’s closure of the Straits ended any prospect of this for the Russians. Neutral Romania denied the use of her railways but agreed to abide by the international character given to the Danube by previous treaties. Russia possessed the port of Reni in the Danube delta, which was linked to the Russian rail net, and this became their major base for shipments to the Serbian river ports of Prahovo and Radujevac. These were located downstream of the Iron Gates, well sheltered from Austrian attack. The Russians formed a special expeditionary force as an independent command under a senior naval captain. The expedition consisted of a naval engineer detachment; mine specialists; a detachment for defense of the Iron Gate region; and another detachment, which was destined to grow, for the transport and protection of supplies.
The first Russian detachment, 106 seamen from the Black Sea Fleet under Senior Lieutenant Volkovitskii, arrived in Serbia at the end of August and set to work installing torpedo tubes and laying mines at various points on the Danube and Save. They also built booms to protect Serbian bridges from floating mines. Another special detachment of seven officers and thirty men with two motor launches and the armed steamer Tiraspol was sent to the region just below the Iron Gates, where they laid minefields, booms, and nets to prevent the passage of vessels and protect against floating mines. The Russians also established two batteries of two 75-mm cannons each, equipped with searchlights, near the border villages.4
The Black Sea Fleet had no warships that could navigate beyond the lower reaches of the Danube, and the Russians were forced to make use of commandeered river craft, specially adapted for military purposes. The first convoy for Serbia sailed from Reni on 14 October and reached Prahovo on the 23d. The Russians sent a total of five convoys to Serbia in 1914 and found that, under favorable conditions and including unloading at Prahovo, the trip upstream required ten days. The convoys were preceded by two armed vessels equipped with minesweeping gear and then, 3 to 4 miles astern, another pair of armed steamers followed by the transports. The Russians appeared more worried by the prospect of air attack than the unlikely appearance of Austrian warships. By the end of March 1915, the Russian Danube forces had grown to 14 steamers, 40 tugboats, and 40 barges with 28 pontoons and docks. Unfortunately, by the summer of 1915, the volume of supplies to be transported far exceeded the capacity of either the Russian or Serbian ports to handle them. The Russians made an effort to improve Reni by reclaiming some of the foreshore and building additional docks with more loading equipment and new approach roads, as well as a railway marshalling yard. The capacity of the little Serbian river ports, however, was minimal, and supplies had to be transhipped twice. A standard-gauge railway line ran from the river ports through the Timok Valley to Zajecar, from which a narrow-gauge line ran through hilly country to connect with the main Nish-Belgrade line at Paracin. There was a potentially important standard-gauge line under construction from Zajecar to Nish that would have linked the Danube ports directly to the main line from Salonika. The Serbians were using Austrian prisoners as labor and hoped to finish the line by the end of the year.5
The lack of transport and unloading facilities frustrated a project by the Russian high command to send troops to Serbia. In February 1915 they investigated the possibility of sending the 53d Caucasian Regiment, to be followed by a militia brigade. This would have involved more than 2,000 men and 1,500 horses; the commander of the special expeditionary force in Serbia had to decline on the grounds that he had neither ships nor barges for the operation. All available shipping had already been mobilized, and the additional ships would have had to come from beyond the Danube.
The Russians also tried to profit from the system by using the return voyage downstream to transport vital war matériel from Britain and France through the Serbian ports to Reni. Between March and May 1915, the Russians reported 10,339 poods (the Russian pood equalled 36.1 pounds) of war matérie
l, including eight aircraft, had been brought by rail from Salonika up through Greece and Serbia and then down the Danube. This was not very much.6
The Danube route was probably the most difficult of the routes to Russia, although certainly far shorter than shipping matériel all the way to the Far East and then back over the Trans-Siberian Railway, and facilities for moving matériel from the north Russian ports at this stage of the war were not much better. The quantities moved were minuscule by the standards of the First World War, and it is hardly surprising that this route has been forgotten by historians. It was possible only while the Greeks were compliant, Bulgaria remained neutral, and Serbia remained free and in the struggle. That situation was destined not to last.
The Russians and Serbians achieved their major success early in the morning of 23 October near Grabovici on the Save when the monitor Temes, flagship of the flotilla, struck a mine and sank with the loss of thirty-one lives, nearly half her complement. The Temes was raised in 1916 after the Serbian campaign, and eventually returned to service. The Austrians attempted to counter the mine danger by fitting their river craft with minenrechens, literally “mine rakes.” These devices were located at the bow and resembled their name, somewhat like the “cow catchers” on mid-nineteenth century American locomotives. They could be lowered in dangerous waters and were fairly effective. Only one other monitor was sunk by a mine during the war. This happened on the Danube, months after the conclusion of the Romanian campaign, and was probably due to a mine that had sunk and been missed by sweepers.7
The French naval mission to Serbia, designated Mission D, consisted of 4 officers and 97 men, three 14-cm cannons, searchlights, and an electrical generator under the command of Lieutenant de vaisseau Edouard Picot. The guns had been taken from the secondary armament of the coast-defense battleship Henri IV, then underemployed as a guardship at Bizerte. The mission came by way of the railway from Salonika, traveling in mufti to avoid offending Greek susceptibilities. The French reached Belgrade the first week in November, but it was not until the 21st that the concrete platforms were finished and the battery ready to open fire. Picot disagreed with the Serbian army’s choice of position, but had to conform. The French employed only two of the guns, and kept the third as a reserve. This subsequently proved to be a fortunate decision.
The French guns fired on the monitor’s anchorage at their extreme range of 10,800 meters. After approximately eleven minutes a British officer observed a hit, apparently at the base of a monitor’s after turret. The monitors raised steam and slipped their moorings. The French guns were an unpleasant development for the Austrian flotilla, for the monitors found themselves outranged. The newly commissioned Enns was the only monitor with larger-caliber guns that could reply, and the French guns were well protected by earthworks. The Austrian flotilla was forced to shift its anchorage 2 kilometers upstream. However, at the end of November the Austrians began another offensive, and the Serbians decided to abandon Belgrade to avoid destruction of their capital. The French naval cannon were immobile, and on the 30th Picot, after rapidly firing off his remaining ammunition, removed the gunsights and breeches from the guns and evacuated his men.8
The Bodrog, Szamos, and Enns covered the entry of Austrian troops into Belgrade on 2 December, but this new Austrian offensive proved to be no more successful than the earlier ones, and on the 14th the Austrians were compelled to evacuate the city. The French moved up the naval gun that had been kept in reserve, and the French navy sent another pair to replace the two that had been abandoned. By mid-February Picot had two guns on Topcider Hill to the south of the city in what he considered a far better position than the earlier one.
The Russians also increased their aid and sent two 15-cm guns, which were emplaced in the Kalimegdan fortress. The guns, however, were very old and one was soon put out of action when a shell exploded in the barrel. Russian assistance in mining was potentially more effective. The Russians and Serbians set about replacing the minefields that had been cleared by the Austrians. The Serbians also completed the demolition of virtually all of the already partially demolished Zemun-Belgrade railway bridge over the Save. The debris made the river impassable under normal conditions and assured that the Austrian vessels west of the bridge in the Save, including the monitors Szamos and Leitha, could not rejoin the remainder of the flotilla. The Austrians found that with the new guns, observation posts, and minefields, the situation around Belgrade was much less favorable in 1915 than it had been in 1914. The French cannon appeared too well protected to be silenced by gunfire from the monitors, and the Austrians realized the best chances for success were in working with the heavy artillery of the army. The activity of the flotilla was greatly reduced during the winter months, and the majority of the vessels went up to Budapest for repair and docking. The headquarters of the flotilla was shifted upstream to Petrovaradin.9
The British had been slower than their allies in sending a naval mission. The Admiralty’s first step in reply to the Serbian request for assistance in dealing with the Austrian monitors was to send Commander Hubert S. Cardale, a member of the British naval mission to Greece, to Belgrade to advise them. Cardale arrived in Belgrade on 30 October. The Admiralty eventually sent a mining and torpedo detachment, a mixed body of approximately twenty-six Royal Marines and seamen under the command of Captain B. N. Elliott, Royal Marine Light Infantry, which reached Belgrade on 7 January 1915. They were followed by a heavy gun detachment of twenty-four seamen and Royal Marines under the command of Lieutenant Commander Charles L. Kerr with eight 4.7-inch naval guns on traveling mountings. The Admiralty blundered, however, as the guns arrived without telescopes for their sights. Moreover, because of the small size of the mission, only three British ratings could be attached to each gun; the remainder of the crew had to be drawn from the Serbian army. The guns were divided into four batteries of two guns each, commanded by a Serbian artillery officer. They were dragged by bullocks to three positions on the Danube and one on the Save, which varied between 2 and 30 miles from Belgrade.10
The Admiralty gave Rear Admiral E. C. T. Troubridge command of the mission. Troubridge, who arrived in Belgrade on 22 February, had commanded the First Cruiser Squadron in the Mediterranean at the outbreak of the war and had been tried by court-martial for failure to engage the Goeben. Troubridge was acquitted, but the Admiralty never employed him afloat again, and the naval mission to Serbia appeared to have been a means of shunting him aside.11 Ironically, it would prove much more adventurous than service in the great majority of naval commands. To avoid duplication of effort or working at cross purposes, the French agreed to serve under Troubridge’s command. The Russians remained somewhat aloof, although they agreed to inform him in advance of their actions.
It was and remains difficult to think of Belgrade and the Danube as more than a secondary front in a largely forgotten campaign of the Great War. But it had the potential to be far more important. The Allied blockade of the Dardanelles and the enforcement of Romanian neutrality in preventing the shipment of munitions and supplies for Turkey by rail through Romania meant that the Danube, whose international status had been recognized, would have been an important route. That route was blocked by the Serbians as long as they controlled Belgrade and the right bank of the river up to their frontier with Bulgaria. In December 1914 the German army high command regarded the reinforcement of Turkey as important enough to send Lieutenant Colonel Hentsch of the general staff to the Danube front to attempt to arrange a munitions transport.
The first attempt to run the gauntlet was on 24 December when the steamer Trinitas and two tugs sailed from Zemun, escorted by the monitor Bodrog, patrol boat b, and armed steamer Almos. The convoy had gotten as far downstream as Semendria when the Bodrog received intelligence warning them of the Russian minefield and log barricade below the Iron Gates. With little possibility of the munitions steamer getting through, the convoy turned back. They were heavily shelled off Semendria but reached Pancsova without serious damage. The
Bodrog reported back to Petrovardin, and the Austrians and Germans decided to abandon the attempt. The monitor Inn was sent to guard the munitions at Pancsova, and on the night of the 30th, with the Almos lashed to the transport to increase its speed against the current, the convoy ran the gauntlet of Serbian batteries and searchlights upstream to safety at Petrovaradin.12 It was a clear demonstration of what a difficult problem supply of Turkey was while the Serbians controlled the approximately 330 kilometers on the right bank of the river between Belgrade and the Bulgarian border. An ordinary steamer would have required roughly 13½ hours to clear Serbian territory, and still would have faced the Russian warships and barricades just below the Iron Gates.
The opening of the Dardanelles campaign and the Anglo-French naval attack on the Strait brought home how desperate the Turkish ammunition situation was, particularly after the Romanians continued to hold back shipments of ammunition by rail. The situation was serious enough for the Austrians to make another attempt to pass munitions by the Danube, although they were not very confident of success. They hoped to take advantage of a rainy and stormy night to run the gauntlet past Belgrade. The steamer Belgrade was loaded with munitions and, under the command of Linienschiffsleutnant Viktor Böszl, left Zemun on the night of 30 March, escorted by the monitors Enns and Bodrog. The little convoy was not detected by the Serbian searchlights around Belgrade, and the monitors returned to their anchorage, according to plan. Unfortunately for the Austrians, several miles downstream the Belgrade apparently hit a Russian mine near Vinca, damaging her rudder and alerting Serbian artillery. The steamer came under heavy fire, was set ablaze, and blew up off Ritopek, killing the captain and the majority of the crew. There were no further attempts to run munitions to the Turks until the Danube was cleared.13
A Naval History of World War I Page 46