A set of four causeways created from blocks of concrete and stone, the Churchill Barriers were designed to protect the eastern approaches to Scapa Flow in the Orkney isles. The barriers, extending to approximately 1½ miles (2.5 km) in length, cross four sounds, linking Mainland Orkney with Lamb Holm, Glimps Holm, Burray and South Ronaldsay. The building of the barriers was prompted during World War II when the German submarine U-47 penetrated the Flow in October 1939 and sank the British battleship Royal Oak with the loss of more than 800 lives. Although the channels had been sealed by blockships, sunk in 1914, these barriers had deteriorated, allowing enough space for the U-boat to pass. Shortly afterwards, on the orders of Winston Churchill (1874 - 1965) who was then First Lord of the Admiralty, plans were drawn up for a series of causeways topped by a roadway which would effectively block the channels. The barriers were designed by Sir Arthur Whitaker, Civil Engineer-in-Chief of the Admiralty, and built by Balfour Beatty Ltd. and William Tawse. Construction began in 1940 and the barriers were completed in 1944 at a cost of £2 million, with an official opening on 12th May 1945 by another First Lord of the Admiralty, A. V. Alexander (1885 - 1965). Around 66,000 huge blocks of concrete were laid on a foundation of more than quarter of a million tonnes of rock, the blocks preventing the tide from sweeping over the road. It took between two and three years for the barriers to rise above the level of the sea. From 1942, Italian prisoners-of-war captured in North Africa undertook much of the work. These prisoners were held in camps on the islands of Burray and Lamb Holm although, after the surrender of Italy in 1943, they were paid a wage and given a considerable degree of freedom.
Today, the Churchill Barriers are Category-A listed owing to their historical importance and carry the A961 road, providing a vital link from the Orkney Mainland to the larger of the southeastern islands in the archipelago. It was only in 2011 that Orkney Islands Council bought the barriers from the Ministry of Defence, at a "nominal sum".
