however, instead they were used to support ground forces during the Battle of Turtucaia and the First Battle of Cobadin, and also took part in the 1917 campaign, contributing to the stemming of the enemy advance. During the Interwar period, the Romanian Danube Flotilla was the most powerful riverine fleet in the world. In 1924, the Romanian river monitors helped suppress the Tatarbunary Uprising, along with the entire Romanian Danube Flotilla. Czechoslovakia had one monitor, , of about 200 tons displacement. She was captured by the Germans in 1939 and commissioned as Bechelaren. She was extensively rebuilt in 1943 and her armament was also modified in February 1945. She supported German troops during Operation Spring Awakening and later fought in Austria, sinking two Soviet gunboats. Yugoslav river monitors were former Austro-Hungarian warships received as reparations. They were renamed (ex-Bosna), (ex-Bodrog), (ex-Enns) and Morava (ex-Körös). After the fall of Yugoslavia in April 1941, Morava (renamed Bosna) and Sava were commissioned by the newly created Independent State of Croatia. Smaller monitors (70–100 ton displacement) were used by Poland in 1939 on the Pripyat River and by the Soviet Union in 1941 on the Pripyat and Dnepr rivers. The Soviet Union also had five Zheleznyakov-class monitors of 263 tons, which served with the Danube Flotilla and Dnieper Flotilla in World War II. Hungary also used river monitors, five of them notably taking part during the Kozara Offensive in 1942. South America The Brazilian river monitor was built for the navy in Rio de Janeiro and commissioned on 9 March 1938. She participated in the Second World War and is currently the world's oldest commissioned warship still in active service. She is assigned to the Brazilian navy's Mato Grosso Flotilla. See also Gunboat List of monitors of the United States Navy List of monitors of the Royal Navy List of monitors of the Swedish Navy List of monitors of the Netherlands References Carrico, John M., Vietnam Ironclads, 2007; Brown Water Enterprises. . Friedman, Norman, U.S. Small Combatants: An Illustrated Design History, 1987; Annapolis: Naval Institute Press. . Kramer, Charles (Illustrator), Popular Mechanics Magazine, 1967; Charles Kramer of Zik Assoc., Ltd. cutaway view of Vietnam "River Battleship". Ship types Riverine warfare Monitors Warships Gunboats