Otranto Barrage

The Otranto Barrage was an Allied naval blockade of the Otranto Straits between Brindisi in Italy and Corfu on the Greek side of the Adriatic Sea in the First World War. The blockade was intended to prevent the Austro-Hungarian Navy from escaping into the Mediterranean and threatening Allied operations there. The blockade, or rather the fleet capital ships in support of it, was effective in preventing surface ships from escaping the Adriatic, but it had little or no effect on the submarines based at Cattaro.

The Adriatic is 72 km (39 nmi; 45 mi) wide at the Otranto Straits. The blockade consisted mainly of a fleet of drifters, most of them British, and usually armed with a 6-pounder gun and depth charges. In 1915 when the blockade was begun, two divisions of 20 would be on patrol at a time, equipped with steel indicator nets intended to trap submarines or at least alert the surface vessels to their presence. A third division would be at Brindisi. The drifters were supported by destroyers and aircraft. However, the demands of the Gallipoli Campaign and other naval operations left the Otranto Barrage with insufficient resources to deter the U-boats, and only the Austro-Hungarian U-6 was caught by the indicator nets during the course of the war. It was later considered that the straits had simply been too wide to be netted, mined or patrolled effectively.

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