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 58 m, a beam of 10.5 m, and a normal draught of 1.3 m. Her displacement was 450 LT, and her crew consisted of 86 officers and enlisted men. The ship was powered using steam generated by Yarrow water-tube boilers, and carried 70 LT of fuel oil. The propulsion system was rated at 1500 shp and she was designed to reach a top speed of 13 kn.

Enns was armed with one triple gun turret of 120 mm howitzers and one double gun turret of 120 mm guns, one double gun turret of 66 mm guns, and seven machine guns. Her armour consisted of belt and bulkheads 38 mm thick, deck armour 25 mm thick, and her conning tower and gun turrets were 51 mm 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 120 mm 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.