Yugoslav monitor Drava The Yugoslav monitor " Drava was a river monitor built for the Austro - Hungarian Navy as Enns " , and was completed in late 1914 . During World War I she was part of the Danube Flotilla , and fought the Serbian and the Romanian Army . After World War I she was provided to the newly created Kingdom of Serbs , Croats and Slovenes ( later Yugoslavia ) . During the German - led Axis invasion of Yugoslavia in April 1941 , she was sunk by German aircraft . She was subsequently raised and scrapped by the Kingdom of Hungary . Description and construction . The " Drava " was built for the Austro - Hungarian Navy as " Enns " by Stabilimento Tecnico Triestino . She was laid down at Linz in 1912 , as part of the Austro - Hungarian 1912 Naval Program , was launched in September 1914 , and completed on 17 October of that year . Along with her sister ship " Bucovina " , she had an overall length of , a beam of , and a normal draught of . Her displacement was , and her crew consisted of 86 officers and enlisted men . The ship was powered using steam generated by Yarrow water - tube boilers , and carried of fuel oil . The propulsion system was rated at and she was designed to reach a top speed of . " Enns " was armed with one triple gun turret of howitzer s and one double gun turret of guns , one double gun turret of guns , and seven machine gun s . Her armour consisted of belt and bulkheads thick , deck armour thick , and her conning tower and gun turret s were thick . " Drava " was launched in September 1914 . Career . " Enns " was commissioned into the Danube Flotilla in October 1914 , and by the following month she was in action against Serbian forces at Belgrade . This continued until October 1915 when the Serbs evacuated Belgrade in the face of an Austro - Hungarian assault . During the final river crossing and support of the resulting bridgehead , " Enns " was near Grosser Krieg Island on 8 October when she received a direct hit below the waterline and her magazine flooded . She was towed out of danger by an armed steamer , and was eventually towed to Budapest where she was repaired . When she returned to the Flotilla she saw action at Rjahovo in early October 1916 , where she contributed to the defeat of the Romanian Flămânda Offensive , which involved a crossing of the Danube to attack the rear of " Generalfeldmarschall " ( field marshal ) August von Mackensen ' s Austro - Hungarian Third Army . In October 1918 , the Danube Flotilla was under serious threat of being cut off in the lower Danube by French forces after the Bulgarians concluded an armistice with the British and French . After the steamer " Croatia " was fired on by the French as it tried to get past Lom , she cut her tow line , releasing seven lighters , which ran aground on a sandbank . The " Croatia " was hit , suffered casualties and grounded on the Romanian side of the river . The French retrieved three of the lighters and towed them into the anchorage at Lom . The following day , " Enns " and two other monitors managed to free three of the remaining lighters while under heavy French fire , and towed them upstream . The Flotilla continued to retreat up the Danube , running the gauntlet of French and Serbian forces . With the dissolution of Austria - Hungary , the South Slavs went ashore at Vukovar , and the German , Hungarian and Czech crew members of the Flotilla continued on their journey , arriving in Budapest on 6 November . Immediately after the armistice , " Enns " was crewed by sailors of the newly created Kingdom of Serbs , Croats and Slovenes ( KSCS , later the Kingdom of Yugoslavia ) in 1918 – 19 . Under the terms of the Treaty of Saint - Germain - en - Laye concluded in September 1919 , " Enns " was transferred to the KSCS along with a range of other vessels , including three other river monitors , and was subsequently renamed " Drava " . With the onset of the German - led Axis invasion of Yugoslavia on 6 April 1941 , " Drava " and the other three monitors steamed upstream to Mohács in Hungary to shell the airfield there , but were subjected to daily attacks by the " Luftwaffe " . On 12 April , with the other three monitors having been scuttled the night before , " Drava " was sunk by " Luftwaffe " aircraft off Čib . She was subsequently raised and scrapped by Hungary .