 In 1915 the light cruisers Melbourne and Sydney were deployed to the Atlantic where they worked alongside the Royal Navy 's North American and West Indies Squadrons , which were engaged in surveillance operations on the large number of German ships that had taken refuge in neutral American ports when the war had broken out . This continued until September 1916 when both cruisers were moved to the North Sea where they joined Australia , which had been assisting the Royal Navy in its blockade of the German High Seas Fleet . 
