 Neither "U-9" nor any of her sister boats were complete when World War I began in August 1914.With the boats under construction at Kiel, the Austrians became convinced that it would be impossible to take delivery of the boats, which would need to be towed into the Mediterranean past Gibraltar, a British territory.As a result, "U-9" and her four sisters were sold to the Imperial German Navy on 28 November 1914.