 In November 1915 , Körös and the other monitors were assembled at Rustschuk , Bulgaria . The position of Romania was uncertain ; the Central Powers were aware that the Romanians were negotiating to enter the war on the opposing side of the Entente . To protect the Danube 's 480 km ( 300 mi ) border between Romania and Bulgaria , the flotilla established a sheltered base in the Belene Canal . When the Romanians entered the war on 27 August 1916 , the monitors were again at Rustschuk , and were immediately attacked by three improvised torpedo boats operating out of the Romanian river port of Giurgiu . The torpedoes that were fired missed the monitors but struck a lighter loaded with fuel . The Second Monitor Division , consisting of Körös and three other monitors , was tasked with shelling Giurgiu . This bombardment set fire to oil storage tanks as well as the railway station and magazines , and sank several Romanian lighters . While the attack was underway , the First Monitor Division escorted supply ships back to the Belene anchorage . The Körös and her companions then destroyed two Romanian patrol boats and an improvised minelayer on their way back to Belene . This was followed by forays of the monitors both east and west of Belene , during which both Turnu Măgurele and Zimnicea were shelled . 
