 Bodrog was part of the Danube Flotilla , and at the start of World War I she was based in Zemun , just upstream from Belgrade on the Danube , under the command of Linienschiffsleutnant ( LSL ) Paul Ekl . She shared the base with three other monitors and three patrol boats . Austria @-@ Hungary declared war on Serbia on 28 July 1914 , and that night Bodrog and two other monitors fired the first shots of the war against Serb fortifications on the Zemun – Belgrade railway bridge over the Sava river and on Topčider Hill . The Serbs were outgunned by the monitors , and by August began to receive assistance from the Russians . This support included the supply and emplacement of naval guns and the establishment of river obstacles and mines . On 8 September , the Austro @-@ Hungarian base at Zemun was evacuated in the face of a Serbian counterattack . Bodrog and the minesweeper Andor conducted a deception operation towards Pančevo on 19 September , and six days later , Bodrog bombarded Serb positions on the bank of the Sava near Belgrade . On 28 September , she rendezvoused with the monitor SMS Szamos at Banovci , and the following day the two monitors targeted the Belgrade Fortress and conducted a reconnaissance of Zemun . On 1 October , Bodrog sailed to Budapest , where she was placed in dry dock for two weeks . She returned to the flotilla on 15 October . By November , French artillery support had arrived in Belgrade , endangering the monitor 's anchorage , and on 12 November , Ekl was replaced by LSL Olaf Wulff . The stalemate continued until the following month , when the Serbs evacuated Belgrade in the face of an Austro @-@ Hungarian assault . On 1 December , Bodrog and the newly commissioned monitor SMS Enns engaged the retreating Serbs . After less than two weeks , the Austro @-@ Hungarians retreated from Belgrade , and it was soon recaptured by the Serbs with Russian and French support . Bodrog continued in action against Serbia and her allies at Belgrade until December , when her base was withdrawn to Petrovaradin , near Novi Sad , for the winter . 
