In March 1918, a United States navy memorandum characterized the Adriatic Sea as “practically an Austrian lake, in which no Allied naval operations of importance are undertaken.”1 The assessment came just four weeks after the Austro-Hungarian navy suffered its worst mutiny of the First World War, foreshadowing the complete collapse of the Dual Monarchy's armed forces, and the empire itself, a mere eight months later. The domination of the Adriatic by Austria-Hungary, right up to the eve of the Armistice, remains one of the more remarkable, and overlooked, dimensions of the conflict of 1914–1918. Indeed, the Dual Monarchy hardly rated as a strong candidate to assert local naval power effectively, even during the long prewar period of peace. Compared to Europe's other five great powers at the turn of the century, only Russia was less urbanized, only Russia and Italy less industrialized, and none had a less extensive coastline. None, too, was so dominated by another great power, as Austria-Hungary depended on its German ally not just for support and protection in the military and diplomatic sense, but also for nearly half of its foreign trade.