Coast Artillery Batteries
In World War One, the main threat to the British Fleet at anchor in Scapa Flow was from surface vessels and submarines. Although the threat of air attack became much more of a reality between the wars, when the time came to rebuild the defences of Scapa Flow there was still a great need to defend against naval attack. During WWII a combination of boom nets, induction loops, controlled minefields, patrolling harbour defence vessels and coast artillery batteries was set up to cover Scapa Flow's entrances, while a ring of heavy anti-aircraft batteries was put in place around the Flow itself to protect the Fleet from attack by the Luftwaffe.
Much of the system of defences against surface and submarine attack early in WWII resembled closely that which had been devised in WWI. A more detailed look at how boom nets, induction loops and minefields, port war signalling and the examination service operated can be found under WWI Defences.
Most of the weaponry and technology of coast artillery had changed very little since WWI. Indeed, many of the guns put in place in Orkney in WWII had started life well before WWI. But later in WWII more modern guns were being introduced. The twin-6 pounder, which later demonstrated its destructive power with such devastating effect in Malta, had been developed between the wars and became a key element in Orkney's defences.
The coast artillery defences were divided into three Fire Commands in WWII known as Northern, Southern and Western. Each of them consisted of a combination of longer range 4.7 or 6-inch calibre guns, supported by quick firing guns such as 12-pounders and twin 6-pounders to tackle fast moving hostile vessels at close range.
Northern Fire Command provided protection for the contraband control area in Kirkwall Bay with gun batteries covering Shapinsay Sound and Wide Firth under a Fire Commander at Rerwick Battery in Tankerness. Southern Fire Command was responsible for the defence of the main southern entrances to Scapa Flow through Hoxa, Switha and Cantick Sounds under a Fire Commander stationed at Stanger Head on Flotta. Western Fire Command defended the western approach and entrance into Scapa Flow through Burra Sound, Hoy Sound and Bring Deeps, commanded from Ness Battery near Stromness.
Just as in WWI, this system of Fire Command allowed the guns to be directed onto specific targets making the defences far more effective than if each gun battery were working independently. It became particularly important when Radio Direction Finding (RDF) or Radar came into operation in coast artillery later in WWII. This technology provided the co-ordinates of targets when visual sighting was not possible and under these conditions the Fire Commander could plot the movements of hostile vessels on a map and provide each of the gun batteries with the information they required to open fire.
The largest calibre armament seen in Orkney was the 6-inch gun, mounted in many of Orkney's coast batteries. It fired a 100lb (45kg) shell which was regarded as the heaviest that one man could carry - this meant that it was not necessary to install complicated and expensive machinery to move and load the shell, so it was quicker and easier to build emplacements. However, this size of gun would not be capable of inflicting serious damage on anything larger than a cruiser. Larger 'counter bombardment' artillery such as the 9.2-inch gun were considered for Orkney, but as the threat from Germany's 'Pocket Battleships' receded, they were never introduced.
Short range quick firing guns were designed to counter what was viewed as the much greater threat to the fleet at anchor of motor torpedo boat (E-boat) or submarine (U-boat) attack. E-boats were capable of travelling at just under 44 knots making them too fast for the large calibre coast guns to track and engage given their slower rate of fire. Initially 12 pounder naval guns were used, as they were in WWI, emplaced overlooking the narrower and sometimes shallower approaches into Scapa Flow and Kirkwall Bay. In August 1940 the first of a new type of coast artillery weapon began to arrive in Orkney to replace the 12 pounders. These were twin 6-pounder guns; two guns mounted together giving a double barrelled appearance within a rotating shield housing. These weapons had a formidable fast rate of fire and were the most advanced coast artillery gun in the British arsenal during WWII.
All gun batteries of both categories were directed from their own Battery Observation Post where the bearing and range to a target would be calculated. Each battery was also equipped with searchlights housed in concrete emplacements. The searchlights, like the guns, came in two categories; dispersed beam and fighting lights. The emplacement of a dispersed beam searchlight had vertical slits in the front through which the light could illuminate an area of water at night and give warning of an approaching vessel. The fighting light had a panoramic opening allowing the beam to illuminate and track a target so that it could be fired upon. Both types were operated remotely from a director station located near to the battery observation post.
Just as in WWI, coast artillery batteries were constructed in remote locations and for the crews manning them, the war would have been one of endurance against harsh weather and basic living conditions as they watched for an enemy that never materialised.