Otranto Barrage

Significance

The Otranto Barrage was an Allied naval operation designed to seal the Strait of Otranto, the narrow southern exit of the Adriatic Sea between Brindisi and Corfu, preventing Austro-Hungarian surface forces from reaching the Mediterranean and disrupting Allied operations there. At its height the barrage employed over 200 vessels. Against surface ships the blockade achieved its primary objective, effectively containing the Austro-Hungarian fleet within the Adriatic for the duration of the operation. Its limitation was equally clear: submarines based at Cattaro were able to pass through or under the barrier with little or no impediment, meaning the undersea threat to Allied Mediterranean shipping remained largely unaddressed. The barrage thus illustrates a recurrent tension in First World War naval strategy between the capacity to interdict surface forces and the difficulty of countering submarine warfare with the technologies and doctrines then available.