Source: ADM 199/184 
            Operation DM4 6.10.39 
            
            OPERATION DM4
            
            From: Vice 
            Admiral, Dover
            Date: 3rd October 1939 
            
            To be carried 
            out, weather permitting, on Friday 6th October 1939. Zero 
            hour 1545 (Subject to confirmation). 
            Ships 
            taking part 
            
            
            Minelayers:       Hampton, Shepperton
            Destroyers:       As detailed by Captain (D) 19
            Minesweepers:  Available ships of 5th M/S Flotilla
            Surveying ship:  Franklin 
            Mines to 
            be laid 
            
            Hampton will lay groups I1, I2, I3 and I4
            Shepperton will lay groups I5 and I6 
            
            
            Embarkation
            
            Mines to be 
            placed alongside the ships at 0700 on Thursday 5th 
            October.
             
            Depth 
            adjustment 
            
              
                | 
                Group | 
                No. of Units | 
                Depth Reel | 
                Chain | 
                Adjustment | 
              
                | 
                I1 | 
                102 | 
                70ft | 
                14ft | 
                Remove 9 ft chain | 
              
                | 
                I2 | 
                10 | 
                60ft | 
                14ft | 
                Remove 4 
                ft chain | 
              
                | 
                I3 | 
                10 | 
                60ft | 
                14ft | 
                Remove 4 
                ft chain | 
              
                | 
                I4 | 
                52 | 
                70ft | 
                14ft | 
                Remove 7 
                ft chain | 
              
                | 
                I5 | 
                220 | 
                50ft | 
                14ft | 
                Remove 6 
                ft chain | 
              
                | 
                I6 | 
                44 | 
                70ft | 
                14ft | 
                Remove 5 
                ft chain | 
            
            
            Procedure
            
            Should it be 
            necessary to postpone the operation the new zero hour will be 
            signalled by Vice Admiral, Dover. After minelayers have left 
            harbour, SO Minelayers is to use his discretion as to postponing the 
            operation should he consider this necessary on account of weather or 
            for any other reason. 
            
            
            Minesweeping
            
            Minesweepers 
            are to leave harbour in time to sweep over line I before zero hour. 
            The depth of the sweep is to be 3 fathoms. When the minelayers have 
            passed the Varne a skimming sweep over the mines just laid between 
            the Searched Channel and the Varne is to be carried out at a depth 
            of 35 feet below the Chart Datum. 
            
            Escort
            
            Captain (D) 
            19 is to detail three destroyers to screen the minelayers during the 
            operation. 
            
            Leaving 
            Harbour
            
            Destroyers 
            are to leave harbour before the Minelayers, SO Minelayers signalling 
            his intended time of departure. FRANKLIN is to leave harbour as 
            convenient for carrying out any necessary surveying work before 
            making a rendezvous with the Minelayers. 
            
            Method of 
            Laying
            
            Line I will 
            be laid from West to East with breaks on the Varne and the Ridge. 
            Hampton will finish her lay on arrival at the Ridge. Shepperton 
            starting after the break. Mines will not be laid within 5 cables of 
            the NE Ridge Buoy. 
            Franklin will 
            lead Hampton onto the line and Shepperton will be stationed 2 ˝ 
            cables on the Port beam of Hampton. On completion of her lay Hampton 
            is to disengage to starboard, increase speed and cross ahead of 
            Franklin from Starboard to Port. This manoeuvre should be carried 
            out as quickly as possible in order not to blank Franklin’s view of 
            fixing points more than necessary. A compromise may be necessary 
            between high speed and prevention of funnel smoke. 
            
            Laying 
            Signals
            The Black 
            Flag will be worked by Franklin as in previous lays but, in view of 
            the breaks in laying, the pendants of the ship to lay will also be 
            flown at the yard-arm. 
            
            Spacing
            
            Mines are to 
            be laid 150 feet apart. 
            
            Return to 
            Harbour
            
            On completion 
            of laying, minelayers are to return to harbour independently. One 
            destroyer is to be ordered to return with Hampton. 
            
            B H Ramsay
            Vice Admiral, 
            Dover