I may end up using these two images several times, as there's a wealth of historical interest contained within them.
These are the complex of structures which made up the Holm Battery, a coastal artillery battery, built for World War 1 and modified for World War 2, to protect the entrance to Scapa Flow via Holm Sound. As a key strategic naval harbour, the Flow was heavily defended by artillery batteries, blockships, and anti-submarine nets. However, it was through Holm Sound during October 1939 that the German submarine U-47 evaded all the defences and sunk the battleship HMS Royal Oak with the loss of 833 lives.
This incident shook the British high command out of their complacent conviction that Scapa Flow was impregnable to submarine attack and, in 1941, work began on constructing the four Churchill Barriers to permanently seal the eastern approaches to the Flow. In many of my sunset photographs taken from Tense Towers, Churchill Barrier One is often visible, linking the Orkney mainland to the island of Lamb Holm.
Target: Holm Coastal Artillery Battery
Location: NGR HY493017
Distance from Tense Towers (as the dragon flies): 500m
Hazards: Cliff edges, sea spray
Mission accomplished: Yes
Comments: The U-47 began its attack on the night of Friday 13th October 1939.