The first shots of World War I were fired by the Austrian monitor "Bodrog", which bombarded Belgrade on 29 July 1914, the day after Austria-Hungary declared war on Serbia. Participating in both surface and submarine warfare in the Adriatic and Mediterranean Seas during the war, the Austro-Hungarian Navy achieved notable victories during the Bombardment of Ancona and the Battle of the Strait of Otranto in 1917. However, the Otranto Barrage, established first by France and eventually maintained by Italy, the United Kingdom and the United States, largely prevented the k.u.k. Kriegsmarine from participating in many naval engagements after 1915. Largely tasked with defending Austria-Hungary's of coastline and of island seaboard for the duration of the war, the Navy chose to rely more on Austria-Hungary's U-boats to engage in offensive naval operations rather than risk the destruction of its battleships, cruisers and other surface vessels. In June 1918, it attempted to break the Otranto Barrage with a massive naval attack which included four dreadnought battleships, four destroyers, four torpedo boats and numerous submarines and airplanes, but the attack was called off after the battleship was sunk by an Italian torpedo boat on 10 June.