Churchill Barriers

used by the Italian POWs, since flooded and converted into a fish farm. In the background at right is barrier no.2 between Lamb Holm and Glimps Holm]] On 14 October 1939, the Royal Navy battleship HMS Royal Oak was sunk at her moorings within the natural harbour of Scapa Flow, by the under the command of Günther Prien. U-47 had entered Scapa Flow through Holm Sound, one of several eastern entrances to Scapa Flow. The eastern passages were protected by measures including sunken block ships, booms and anti-submarine nets, but U-47 entered at night at high tide by navigating between the block ships. To prevent further attacks, First Lord of the Admiralty Winston Churchill ordered the…

The contract for building the barriers was awarded to Balfour Beatty, although part of the southernmost barrier (between Burray and South Ronaldsay) was sub-contracted to William Tawse & Co. The first Resident Superintending Civil Engineer was E K Adamson, succeeded in 1942 by G Gordon Nicol. Preparatory work on the site began in May 1940, while experiments on models for the design were undertaken at Whitworth Engineering Laboratories at the University of Manchester. The bases of the barriers were built from gabions enclosing 250,000 tonnes of broken rock, from quarries on Orkney. The gabions were dropped into place from overhead cableways into waters up to 18 m deep. The bases were then…