Enemy Recognition Signals. 1. British Destroyers and T. B.'s use special lights for the purpose of distinguishing themselves during darkness or fog. These are:- Two green lamps 2 m. apart, horizontally on the starboard yard, and two red lights horizontally on the port yard. The lamps are visible all round and may only be used in action, and not as ordinary recognition signals. In addition to these, steaming and side lights are to be burnt. (Admiralty Order of 3/9/14). 2. From an order issued to the British submarine E. 15 it appears that a two-letter recognition signal, made by searchlight or flashing lamp, and changing at 12 midnight, local time, is used. (Recently three-letter signals have been used). (Order dated end of March, 1915). This confirms observations of British recognition signals as made by cruisers. It is desirable, therefore, in case deception is intended, to call English ships with badly manipulated searchlights, and to give a two-letter challenge in the hope of their not taking special care to see that the exact challenge is made. 3. By Admiralty Order of 16th November 1914, in order to avoid confusion owing to the dangerous similarity between the German and British Naval Ensigns all ships and vessels carry at sea, in addition to the white ensign, at least one red ensign in a conspicuous position on or near the foremast. Destroyers and T. B.'s fly the Red Ensign at the Yardarm in such a manner as to leave the mast-head free for signalling. (According to observations made by a fishing vessel on 31/9/15 this order is still in force. The vessel reported: "The Senior Officer's ship of the Destroyers was flying the Red Ensign forward on the mast, the remainder carried a small plain red flag aft on the mizzen. Perhaps this 'small red flag' may only have been a smaller red ensign than that flown by the Senior Officer's ship"). (manuscript addition to para 3.) According to observations made in the action on the 17th November 1917, English Light Cruisers and destroyers flew a large pendant at the foremast; the colour could not be distinguished. (C-in-C. ii VI of 11th January 1918). 4. As recognition signals between enemy allied naval forces, red and white horizontal lights are shown at the foremast at night. The lights are shown as soon as a vessel is sighted. By day several letters are morsed by searchlight. How often and when the letters are changed is not known.