Although two monitors had been put out of action, the tide of battle was turning. The French battery on Topcider, which had been so effective against the monitors, was finally silenced by a direct hit from a 30.5-cm mortar. The Körös and Leitha were effective in providing close support for the Austrian bridgehead, and in the southwestern suburbs the Germans were able to consolidate their bridgehead opposite Great Tsiganlia Island. The picket boat on which so many hopes had been expended was destroyed in the shelling, sparing the British the necessity of scuttling it. The British naval mission was able to evacuate the majority of their guns, although they would have to be abandoned in the ensuing weeks during the long retreat. The Austrians and Germans succeeded in consolidating their positions, and downstream to the east the German Eleventh Army, with the assistance of the Kaiserliches Motorbootkorps, successfully completed their crossing of the Danube in the vicinity of Semendria on the 9th. The Danube Flotilla minesweepers were already hard at work clearing the river of mines by the time the last heights to the south, southwest, and southeast of Belgrade were captured by the Austrians and Germans on the 11th. The Austrians were now free to use the Danube past Belgrade.32
From the point of view of naval operations, the Serbian campaign was now over and the Danube open to the Bulgarian frontier. The Russian naval mission made a desperate effort to prevent this before leaving Serbia. Captain Illin of the Russian navy led an attempt to blow up the canal in the Danube at Orsova by excavating under the narrow canal and blowing up the bottom to create an overfall that would make navigation by barges impossible. Troubridge was asked to cooperate, and on 19 October supplied two thousand pounds of gun cotton along with a gunner and two petty officers. He did not believe there was much chance of success, for the project had not been well thought out and no preparations had been made for it. His fears proved correct two days later when the demolition party reached their destination and began work. They immediately came under the fire of Austrian guns on the opposite bank of the river and were forced to abandon the operation. The party narrowly avoided capture by the Bulgarians on their return to Serbian headquarters.33
The land campaign lasted until the end of November with the Bulgarians cutting off the route from Salonika and preventing an Anglo-French force under General Sarrail from moving up the Vardar Valley to the assistance of the Serbians.34 The British and French ended by holding the area around Salonika and opening yet another front of the war in Macedonia. The Germans had no immediate interest in taking Salonika and even requested the Bulgarians to refrain, at least for the time being, from crossing the Greek frontier. The Allied naval missions joined the general retreat of the Serbian army. Some were eventually evacuated by way of Salonika, whereas Troubridge and most of the British joined the Serbian army in its epic retreat through the mountains of Albania to the Adriatic coast where they were eventually evacuated to Corfu.35
The Austrian Danube Flotilla proceeded downstream to Orsova, on the Hungarian-Romanian frontier, where it waited while sweepers cleared the Danube channels of mines and log booms along the Serbian shore so that the first shipments of munitions to Turkey and Bulgaria could be made. The Danube Flotilla then escorted the first convoy, which arrived at the Bulgarian port of Lom-Palanka on 30 October, where matériel was unloaded for shipment over the Bulgarian railways to Turkey. The shortage of rolling stock at Lom-Palanka soon led the Austrians to move two armed transports and six tugs farther downstream to the Bulgarian ports of Svistov and Rustschuk. By the second half of November, some ten munitions shipments had taken place without incident, and the Austrians no longer felt that it was necessary to directly escort them. The armed Russian steamers on the Danube had either sought shelter in Romanian ports or had moved downstream to Russian territory, but there was always the possibility the Russians would attempt to mount some naval operation from Reni. On 12 November AOK therefore ordered the monitors to concentrate at Rustschuk.36
The potential importance of the Danube to the Central Powers, cut off from access to the high seas by the British blockade, was obvious. There were, however, considerable navigational difficulties in moving cargo upstream because of the rapids at the Iron Gates. These rapids in the past had virtually prevented navigation between the upper and lower Danube. Between 1891 and 1896 the Hungarian government had cut a canal roughly 2.5 kilometers in length on the Serbian side of the river. This was later supplemented by the cable tug Vaskapu, which used a cable laid in the stream to gain extra traction to assist tugs in hauling loads against the current.37 The Vaskapu was captured by the Serbians at the beginning of the war, and the Germans therefore took the initiative in building a towing railway along the canal that was ready at the end of May 1916. A powerful steam locomotive could now assist tugs in working upstream. Some idea of the increased importance of the Danube can be obtained from the tonnage moved upstream and downstream through the Iron Gates from 1900 to 1922. The tonnage in 1916 and 1917 was more than twice and in 1918 almost twice that of the best year (1909) before the war.38
THE ROMANIAN CAMPAIGN
The Austrian navy, joined by the German motorboats, was now faced with the problem of defending traffic on the Danube and the Bulgarian frontier with Romania. The Danube formed the border between Romania and Bulgaria from the Serbian border to about 10 miles west of Tutrakan on the right bank, where the border ran southeastward to the Black Sea. This region between the right bank of the Danube and the Black Sea was known as the Dobrudja and had been lost by the Bulgarians after the Second Balkan War in 1913. The Austrians and Germans patrolled the Danube with a variety of river craft, but Romania, courted by the Entente, could not be trusted and controlled the entire left or north bank of the Danube—more than 300 miles—along the Austrian line of communications. It was, to say the least, a potentially awkward situation.
The Austrians found a way out of the difficulty by establishing a base in the Belene Canal. This arm of the Danube, a few miles upstream from the Bulgarian town of Svistov, was separated from the main part of the Danube by the large island of Persina and provided the Donauflottille with an anchorage sheltered from artillery fire from the Romanian shore. The Bulgarian shore for much of the Danube was higher than the Romanian side, where the shore was frequently swampy, full of lagoons and lakes, and where high ground began some distance from the river. The Austrians improved communications with the Belene base by building a light horse-drawn railway to connect with the nearest Bulgarian railway station. They also ran new telephone and telegraph lines. In time of war the entrance to the Belene arm could be protected by booms and mines as well as artillery batteries on the Bulgarian shore.
The Romanians bargained long and hard with the Entente over their entry into the war, and probably missed the opportune moment when the Austrians had been badly battered by the Brusilov offensive on the eastern front in June of 1916.39 This was the last great success of the old Imperial Russian army, but by the time the Romanians concluded a treaty with the British and French on 17 August and declared war on the 27th, it had bogged down and the Central Powers had recovered their equilibrium. Furthermore, it gave Germany and Austria-Hungary time in which to make preparations. On 29 July the Germans, Austrians, and Bulgarians reached an agreement, later adhered to by the Turks, on the conduct of the campaign. Field Marshal Mackensen was given command of the southern frontier, that is, the region of the Dobrudja and Danube. AOK decided to retain the majority of the Danube Flotilla in the lower Danube rather than ordering it to make the long trip upstream from Rustschuk. After hostilities began, the flotilla, including the monitors at Rustschuk and the armed steamers spread along the Danube, proceeded to Belene; only the armed steamer Almos and patrol boats Lachs and Stör were upstream at Kladovo, and there were a few German motorboats at Orsova. The Austrians also sent special bridging equipment down to Belene in a few echelons in preparation for a future crossing of the Danube. On 13 August the Danube Flotilla was placed under the orders of Army Group Mackensen.
Mackensen divide
d the forces along his lengthy front in two, a “Danube army,” which would initially remain on the defensive, and a “Dobrudja army,” consisting of one German, four Bulgarian, and two Turkish divisions, which would advance into the Dobrudja. Once Mackensen had reached an agreed-upon line in the Dobrudja, he would shift substantial forces back to the region of Svistov, cross the Danube, and drive on Bucharest. The offensive into the Dobrudja was deliberately designed to take the pressure off the Austrians on the Hungarian-Romanian border. The Germans and Austrians correctly anticipated that the Romanians would put their major military effort into an advance into Transylvania, where they had territorial designs, and leave the defense of their southern frontier to smaller and weaker forces. The defense of Hungary was entrusted to the Austro-Hungarian First Army under General Arz von Straussenberg, a comparatively weak force of two battered infantry and one cavalry divisions drawn from the eastern front, and miscellaneous second line units. The Germans promised to reinforce Arz with five infantry divisions and one or two cavalry divisions. The Austrians, who sought desperately to build up their forces in Transylvania, were put under additional pressure by an Italian offensive along the Isonzo in early August that captured Gorizia and forced them to shift additional forces from the eastern front to the Italian front.40
Romania’s declaration of war on the evening of 27 August might have been overly delayed from the British and French point of view, but it caught the German general staff by surprise, for they had not expected the Romanians to enter the war until after the Romanian harvest in mid-September. The Romanians, on paper, had an army of more than 560,000 men, organized into four armies and twenty-three divisions, although thirteen were either second line or partial formations. The Romanian soldiers were predominantly sturdy peasants, but by most accounts they were poorly led and their army deficient in communications, artillery, supply and technical services, and aviation, although they later received some air support from the Russians and French.41
The Romanian navy was small and had never been able to fulfill its ambitions to become a significant force in the Black Sea. Under the naval program of 1899, the Romanians would have had six coastal battleships, four destroyers, and twelve torpedo boats, but none of these ships were ever built. The 1912 program called for six 3,500-ton light cruisers, twelve 1,500-ton destroyers, and a submarine. Four destroyers were actually ordered and laid down in Italy, only to be requisitioned by the Italian navy on the outbreak of the war. The largest Romanian warship in 1916 was the old (1888) protected cruiser Elisabeta, whose main armament of four 12-cm guns was landed for use in the fortifications on the left bank of the Danube opposite Tutrakan; she served merely as a guard ship at Sulina. The Romanians also had four old gunboats (110 to 116 tons), which dated from the 1880s and were of doubtful utility, and three old French-built, 56-ton Naluca-class torpedo boats. The most useful Romanian contribution in the Black Sea were the four relatively modern liners Regele Carol I, Dacia, Imparatul Traian, and Rumania, which were converted into auxiliary cruisers and used to good effect by the Russian Black Sea Fleet as seaplane carriers (see chapter 8).
The Romanians in the years just before the war had tended to neglect their seagoing forces in favor of their Danube division, which was somewhat more modern. They had four potentially useful monitors, Lascar Catargi, Ion C. Bratianu, Alexandru Lahovari, and Mihail Kogâlniceanu, built in Trieste in sections and assembled at Galatz in 1907 and 1908 with a primary armament of three 12-cm cannons and eight British-built (1906–7), Capitan Bogdan-class, 50-ton torpedo boats. There were also five to six older gunboats, used for police purposes, and a number of miscellaneous river craft used as transports, supply ships, or minelayers.42
The Romanian navy commenced hostilities on the Danube at approximately 9:30 on the night of 27 August. The Romanians sought to whittle down Austrian naval superiority by a surprise torpedo attack on the monitors at anchor off the Bulgarian port of Rustschuk.43 Three improvised torpedo boats crept out of the Romanian port of Giurgiu across the river and fired five torpedoes and dropped a few mines. The torpedoes missed the Austrian flagship, the monitor Bosna, but hit a nearby naval barge loaded with coal and petrol. The barge burned and sank, although Austrian accounts indicate the flotilla had not yet received word of the declaration of war and attributed the explosion at first to spontaneous combustion or the crew’s carelessness with open flame near the petrol. The Austrians immediately executed their plan to withdraw to the Belene Canal, with the First Monitor division convoying the noncombatant supply ships while the Second Monitor division (the Bodrog, Körös, Szamos, and Leitha) with six patrol boats, using lighters to screen against torpedoes, proceeded to an advantageous position to shell the harbor of Giurgiu. Simultaneously, the patrol boats moved in to recover as many Austro-Hungarian lighters from Giurgiu as possible. The monitors then opened fire, setting oil storage tanks, the railway station, and magazines along the shore ablaze and sinking a number of Romanian lighters.
Following the attack the monitors proceeded upstream, destroying two Romanian patrol boats, whose crews had run them ashore behind mines. They reached the safety of Belene in late afternoon of the 28th. On their way they met and promptly sank the Romanian steamer Rosario, which had been fitted as a minelayer. The German gunboat Weichsel, which had been acting as a guardship east of Rustschuk, also arrived safely under cover of darkness. Far upstream, the armed steamer Almos and patrol boats at Kladovo successfully ran the gauntlet of hostile artillery to reach the safety of Orsova on the night of the 28th.
The Danube Flotilla carried out offensive sorties to the east and west of Belene on the 29th, shelling Turnu Magurele and Zimnicea and capturing a number of lighters; the next day, however, Romanian artillery frustrated an attempt to recover more lighters from Giurgiu.
The army high command ordered the Danube Flotilla to remain inactive in September while operations on land took their course. The flotilla was secure in the Belene Canal, although the Romanians brought up heavy batteries to the heights around Zimnicea within range of the eastern portion of the canal and forced the flotilla to shift its anchorage. The Romanians also launched a number of unsuccessful air attacks. The monitors returned to offensive operations on 29 September, when the Inn and Sava led the patrol boats Viza, Barsch, and Csuka, the gunboat Weichsel, and the armed steamer Samson on an offensive sortie to Corabia where they set fire to the railway installations, destroyed many of the Russian ships taking refuge in a swampy arm of the Danube, and towed off nine lighters, two of them fully loaded.44
There is little doubt that the Austro-Hungarian Danube Flotilla had command of this portion of the Danube, the areas within easy steaming distance of the Belene Canal. However, one must also remember that this was the back door of the Romanian defenses, and the efforts and attention of the Romanians were focused on other areas, the Dobrudja and Transylvania. Three of the four Romanian armies had been used for the advance into Transylvania; only one was left on the Bulgarian frontier. The flotilla could do nothing to affect the fighting in the Transylvanian mountains, and a strong Romanian mine, boom, and artillery barrier near the frontier east of Rustschuk at Kalimok prevented any movement by the Austrian flotilla to the Dobrudja. These barriers could not be cleared until both banks of the Danube were in the hands of the Central Powers. The Romanian campaign was decided by the fighting on land.
The Romanian invasion of Transylvania made good progress at first against the outnumbered Austrians. The Germans and Austrians, however, enjoyed the advantage of inner lines and a superior rail network, and the Germans were able to rush the reinforcements they had promised the Austrians before the war. General von Falkenhayn, recently relieved as chief of the German general staff, assumed command of the German Ninth Army (three German and two Austrian divisions), which formed to the south of Arz’s First Austrian Army (one German and four Austrian divisions). By mid-September the Romanian advance had been brought to a halt.45
In the south Mackensen began his attack on the Dobru
dja the night of 1 September, and by the 5th and 6th broke through the Romanian defenses and captured the frontier fortress of Tutrakan on the right bank of the Danube. The combined Bulgarian, Turkish, and German forces were soon threatening the important railway line between Bucharest and Constanza, Romania’s major port on the Black Sea. The Russians rushed three divisions and a Serbian volunteer division to the Dobrudja, joined by three Romanian divisions shifted from Transylvania. Russian engineers also bridged the Danube in the region of Reni to move troops and supplies.46 Mackensen’s advance was halted, but only for a short time; on 23 October he captured Constanza and the main line from Bucharest. The war turned against the Romanians in Transylvania as well. On 30 September Falkenhayn defeated the Romanians at Hermannstadt, and on 8 October at Kronstadt, driving them back into the mountain passes between Transylvania and Romania where they were now on the defensive trying to stop an Austro-German advance into the Romanian plains.
What of the Romanian navy? The monitors assisted in the defense of Tutrakan and then supported the Danube flank of the Romanian and Russian army in the Dobrudja. On 6 September three Russian gunboats, the Kubanetz, Donetz, and Teretz, arrived in the Danube as reinforcements. The three 1,280-ton gunboats had been launched in 1887 but modernized before the war. They were armed with two modern 6-inch guns mounted in sponsons, a 4.7-inch gun aft, and two 11-pounders. The Donetz had been sunk at Odessa in the surprise attack that opened the war in the Black Sea but had been salved and repaired. The gunboats had gone up to Silistria at first, and in order to get that far up river they had to be lightened of all ammunition, coal, and boiler water, and then towed. Unfortunately, Tutrakan fell as they arrived, and with the Romanian retreat they had to move back downstream, although a propitious rise in the level of the river spared the Russians from the arduous task of lightening ship once again in order to pass the sandbanks. There were other Russian naval forces on the Danube, according to a British observer, including five to six Azov steam “schooners” (grain steamers), four small destroyers, three old torpedo boats, four motor patrol boats, a small submarine at Reni, armed tugs, river steamers, and hospital barges.47 The Russians also sent mine specialists and sailors, coastal torpedo tubes, and field artillery drawn from the front in the north.
A Naval History of World War I Page 48