The original dam was built between 1934 and 1938 from earth and stone, with an inner lining of loam, coming into service in 1939. During the Second World War, on February 10, 1945, to impede the advance of the Anglo-Canadian 21st Army Group during Operation Veritable, water was released from the sluice gates; this delayed supportive action (Operation Grenade) by the American Ninth Army for two weeks. Construction from 1955 to 1959 raised the height of the dam by 20 meters to its present height of 77 meters above the riverbed.