On Jellicoe's advice, Dreyer was given command of the scout cruiser HMS "Amphion" in 1913, with promotion to captain in June. That year "Amphion" came first out of the entire navy in the gunlayer's test and first in the vessel's type in battle practice. In October, 1913 he became flag captain (commander of the flagship) to Rear Admiral Sir Robert Arbuthnot in the battleship HMS "Orion" (flagship Rear Admiral 2nd Battle Squadron) until 1915. At the behest of Jellicoe, now Commander-in-Chief of the Grand Fleet, Dreyer was made flag captain of HMS "Iron Duke", serving at the Battle of Jutland in 1916.