Scapa Flow: Britain's Premier Naval Anchorage in Two World Wars

Strategic significance and origins as a naval anchorage

Scapa Flow is one of the great natural harbours of the world — roughly 312 square kilometres (120 sq mi) of sheltered water, almost entirely enclosed by the Orkney Mainland to the north, Hoy to the west, South Ronaldsay to the south-east, and the smaller islands of Burray, Flotta and Graemsay. Its shallow, mostly sandy bottom (generally around 30 m, nowhere deeper than about 60 m) and its ring of islands gave anchorage on a scale that could hold several navies at once. Its waters had been used since prehistory, and Viking longships anchored there over a thousand years ago.

The strategic logic that brought the Grand Fleet north in 1914 was geographical. Historically Britain's main naval bases lay near the English Channel to face France, Spain and the Netherlands; Germany had never been a traditional maritime enemy. The build-up of the Kaiserliche Marine changed this. From 1904 the Admiralty recognised the need for a base that commanded the northern exit from the North Sea — the "hinge of the door" that could bottle up the German fleet and enforce the distant blockade that ultimately strangled Germany's war economy. Scapa Flow was ideally placed: it barred the northern route to the Atlantic while giving the fleet ready access to open water. Crucially, unlike the Firth of Forth, it could not easily be sealed by a minefield laid across its mouth, which risked trapping the fleet in its own base.

The base's great weakness was that it was almost undefended when war came. Admiral Jellicoe, commanding the Grand Fleet, was perpetually anxious about submarine and destroyer attack — a fear vindicated when a U-boat was detected attempting to enter in November 1914. Defences were then improvised at speed: blockships sunk in the eastern channels, anti-submarine indicator nets, booms, minefields and coastal batteries. The base was declared safe in 1915. It was from Scapa that the Grand Fleet sailed to fight the Battle of Jutland (31 May–1 June 1916).

The comparative significance question versus the Firth of Forth

Card #35's scholarly source — Gordon J. Barclay and Ron Morris, The Fortification of the Firth of Forth 1880–1977 (Society of Antiquaries of Scotland, 2019) — argued that the Forth's naval history has been "unjustly eclipsed by the mythologisation of Scapa Flow." In their own words, "the mythologisation of the wars has led to the entire naval experience being focused on Scapa Flow, the fleet's operational base in Orkney," while the memory of "the estuary filled with ships, sheltering behind the defences, had almost slipped from history." Their book takes its subtitle from a 1922 assessment describing the Forth Fortress as "the most powerful naval fortress in the British Empire."

Presented evenhandedly, the evidence supports a nuanced verdict rather than a simple contest. On one hand, mainstream naval scholarship is united that Scapa Flow genuinely was the Royal Navy's principal fleet base: the naval historian Brian Lavery describes it as "the Royal Navy's main fleet base during two world wars," and the same judgement runs through the Imperial War Museum, Historic Environment Scotland, and standard reference works such as Dan van der Vat's account of "the British Grand Fleet's principal anchorage at Orkney." On the other hand, Barclay and Morris are factually correct on two points that puncture any myth of Scapa's exclusive primacy: first, the battlecruiser force under Beatty was based at Rosyth on the Forth throughout much of WWI; and second, by April 1918 the Grand Fleet's main body itself had relocated to Rosyth once the Forth's anti-submarine defences were complete, and in 1919 Rosyth — not Scapa — became the fleet's main base.

The fairest conclusion is that Scapa's popular pre-eminence is not undeserved — it was the base at the moments of greatest danger and the scene of the two most dramatic events in the anchorage's history (the scuttling and the Royal Oak) — but that its dominance of public memory has indeed overshadowed the equally real and, in some periods, greater importance of the Forth. Barclay and Morris themselves concede Scapa was "the base of the main home fleets" during "times of great danger"; their argument is about imbalance in remembrance, not a denial of Scapa's role. This card therefore treats Scapa as a genuinely distinct and primary subject while acknowledging the corrective the Forth's scholarship provides.

The German High Seas Fleet internment and 1919 scuttling

Under the Armistice of 11 November 1918, the German High Seas Fleet was to be interned pending a final peace settlement. In Operation ZZ (21 November 1918), an enormous Allied escort brought the German ships across the North Sea; 74 vessels were ultimately interned at Scapa Flow, their crews kept aboard while diplomats at Paris argued over the ships' fate. Conditions aboard deteriorated over the following seven months — supplies from Germany ran low, discipline frayed, and morale collapsed.

The fleet's commander, Rear Admiral Ludwig von Reuter, had prepared for scuttling. His secret written order of 17 June 1919 (its "Paragraph Eleven") instructed that the ships be sunk only in the case of forcible intervention by the British or on his special order, stating: "It is my intention to sink the ships only if the enemy should attempt to obtain possession of them without the assent of our government." Reading a several-day-old copy of The Times, von Reuter concluded that the peace terms demanded the fleet's surrender, that his government would refuse, and that the British would therefore seize the ships when the Armistice expired (as he believed) on 21 June. When the British 1st Battle Squadron, under Vice Admiral Sir Sydney Fremantle, left the Flow for exercises on the morning of 21 June, von Reuter seized his chance.

At approximately 11:20am he transmitted the signal "To all Commanding Officers … Paragraph Eleven of to-day's date. Acknowledge." Seacocks, torpedo tubes and portholes were opened across the fleet. Within about five hours, 52 of the 74 interned ships sank — an equivalent of about 400,000 tons of material — comprising 15 of the 16 capital ships (10 battleships and 5 battlecruisers), 5 of 8 light cruisers, and 32 of 50 destroyers. British guard vessels beached what they could — one battleship (Baden), three light cruisers and 14 destroyers. Nine German sailors were shot dead and 16 wounded by British crews trying to force them to stop; these were the last casualties of the First World War, which formally ended with the signing of the Treaty of Versailles on 28 June 1919. The Imperial War Museum records the event as "representing the greatest loss of shipping in a single day in history."

A flagged dispute: whether von Reuter genuinely did not know the Armistice deadline had been extended to 23 June is genuinely contested. The Imperial War Museum states the extension was "unknown to von Reuter"; other scholarly accounts (including the Western Front Association's) hold that he had been informally told by the British and acted anyway. Von Reuter maintained he had not been advised; the British counter-claimed he had. We present this as an unresolved documented dispute rather than settled fact. Von Reuter described his fleet's condition in his own words as "Wehrlos, ehrlos" — "disarmed, dishonoured."

Salvage and surviving wrecks: During the interwar years most of the fleet was raised in one of the greatest feats of marine salvage ever attempted. Ernest Cox's firm Cox & Danks pioneered the technique of pumping compressed air into upturned hulls to refloat them; between 1924 and 1932 they raised dozens of vessels, and Metal Industries Ltd continued the work until 1939. Cox famously used the exposed coal bunkers of the battlecruiser Seydlitz as his own "coal mine" during the 1926 General Strike. Seven vessels proved too deep to salvage economically and remain on the seabed: the battleships König, Kronprinz Wilhelm and Markgraf, and the light cruisers Brummer, Dresden, Cöln and Karlsruhe. All seven are protected scheduled monuments and are covered by the Historic Environment Scotland designation record for the scuttled High Seas Fleet.

The sinking of HMS Royal Oak, 14 October 1939

When war returned in September 1939, Scapa Flow was again chosen as the Home Fleet's base, principally because of its distance from German airfields. But the WWI defences had decayed: anti-aircraft cover was inadequate, the anti-submarine nets were poor, and — decisively — the blockships in the eastern channels had rotted and shifted. Surveys in 1938–1939 had shown that navigable gaps remained through Kirk Sound and Skerry Sound; a new blockship, the Soriano, sunk in Kirk Sound in March 1939, failed to close the channel. Admiral Karl Dönitz, studying reconnaissance of the base, concluded that a submarine could penetrate at Kirk Sound at the turn of the tide "without further ceremony."

He was proved right. On the night of 13–14 October 1939, U-47, commanded by Kapitänleutnant Günther Prien, entered Scapa Flow on the surface through Kirk Sound at high tide, passing the blockship Soriano and the shore in a narrow navigable gap. Much of the Home Fleet was absent — dispersed after German air reconnaissance — leaving few targets. Prien found the elderly battleship HMS Royal Oak at anchor in the north-east of the Flow. His first salvo shortly after 00:58 produced only a muffled explosion that the crew mistook for a minor internal fault; no alarm was raised. Prien reloaded and fired again at about 01:16. This second salvo of three torpedoes struck amidships, detonating a magazine; Royal Oak rolled over and sank within about 13 minutes. Of her complement of 1,234, 835 were killed — a figure revised upward from the long-quoted 834 after research in 2019 identified a man who died of burns two weeks later. The dead included Rear-Admiral Henry Blagrove and 134 boy seamen under the age of 18, the largest such loss in a single Royal Navy action. The drifter Daisy II, moored alongside as tender, saved 386 men. U-47 escaped back through Kirk Sound; Prien became a national hero in Germany, the first U-boat officer to receive the Knight's Cross, nicknamed "the Bull of Scapa Flow."

Mythbusting. The event generated durable myths that the site's "accuracy over patriotism" standard requires we separate from fact:

• The spy legend — that a German agent, "Alfred Wehring," living in Orkney as a Swiss watchmaker under the name "Oertel," guided U-47 in and escaped aboard the submarine — is fiction. It originated in a 1942 article by the journalist Curt Riess and has no basis in the record; U-47 navigated by chart, tide tables and Prien's seamanship.
• Prien's ghost-written "autobiography," Mein Weg nach Scapa Flow (1940), was a propaganda product edited by the German high command; Prien himself made angry corrections, and the ghost-writer later called the account "demonstrably false."
• The German command concealed that several of Prien's torpedoes failed to detonate — part of the chronic torpedo-reliability problems that plagued the U-boat arm.
• The popular framing of Scapa as an "impregnable base" was itself an overstatement: the Admiralty and local commanders knew the eastern channels were vulnerable, and the subsequent Board of Inquiry unfairly scapegoated the retired Admiral Commanding Orkney and Shetland, Sir Wilfred French.

The Churchill Barriers and wartime defensive improvements

The loss of Royal Oak forced decisive action. Winston Churchill, again First Lord of the Admiralty, ordered the eastern approaches sealed permanently. The result was the Churchill Barriers: four causeways of rubble and concrete blocks linking the Orkney Mainland to Lamb Holm, Glimps Holm, Burray and South Ronaldsay. Construction by Balfour Beatty & Co. began in May 1940 and used enormous quantities of quarried rock and concrete blocks of 5 and 10 tonnes. The project faced a labour shortage that was solved from early January 1942 by the arrival of more than 1,300 Italian prisoners of war captured in North Africa, divided between three camps — around 600 at Camp 60 on Lamb Holm and about 700 in two camps (including Camp 34) on Burray, with the peak labour force in 1943 exceeding 2,000. Because prisoners could not, under the Geneva Convention, be compelled to do war work, the barriers were officially described as causeways linking the islands — which is what they remain. The work was substantially completed by September 1944, and the barriers were formally opened as public roads on 12 May 1945, days after VE Day; their lasting role has been as road links rather than as fleet defences. Scapa Flow's WWII defences also included a thickened ring of coastal batteries, anti-aircraft positions, observation posts, and anti-submarine booms across the remaining entrances at Hoxa and Switha Sounds.

The Italian Chapel is a related but distinct heritage site. In 1943 the men of Camp 60, led by the artist Domenico Chiocchetti, converted two Nissen huts into an ornately decorated Catholic chapel, using materials salvaged from blockships and improvised from scrap. It was not fully finished when the Italians departed in 1944; Chiocchetti returned to restore it in 1960 and on later occasions until his death in 1999. It is a Category A listed building and one of Orkney's most visited attractions — a monument to the prisoners and to the Orcadians who befriended them.

Current heritage status and legacy

Scapa Flow today is one of the world's great wreck-diving destinations and a landscape-scale memorial to 20th-century naval history. The seven surviving German High Seas Fleet wrecks are protected scheduled monuments; diving is permitted but removing artefacts is a criminal offence. The two Royal Navy war graves — HMS Royal Oak and HMS Vanguard — are protected under the Protection of Military Remains Act 1986, and diving on them is prohibited except for licensed Royal Navy operations. The Royal Oak's ensign is renewed annually by Navy divers. Following a designation announced by the Scottish Government in August 2025, Scapa Flow became a Historic Marine Protected Area with effect from 1 November 2025, recognising a site that "has a number of different historic marine assets including the largest concentration of warship wrecks and other wartime artefacts in the UK" and making it a criminal offence to remove, alter or disturb protected features. The Scapa Flow Museum at Lyness on Hoy — housed in a former 1937 naval oil pumphouse and reopened on 2 July 2022 after a £4.4m redevelopment — is the definitive interpretive centre, and was named one of five Art Fund Museum of the Year finalists in 2023.

• The scuttling of 21 June 1919 remains the greatest loss of shipping in a single day in history — an equivalent of about 400,000 tons of warships went to the bottom in roughly five hours.
• The nine German sailors shot during the scuttling were the last casualties of the First World War, which formally ended a week later with the signing of the Treaty of Versailles on 28 June 1919.
• Ernest Cox raised battleships by turning them into giant airtight vessels and floating them upside down — and a maintenance "running crew" lived in huts bolted to the upturned hulls as they were towed to the breakers at Rosyth.
• The floating dock Cox used to lift the German ships had itself been seized from Germany as war reparations for the scuttling — a neat historical irony.
• HMS Vanguard's loss in 1917 (843 dead from an accidental magazine explosion) remains the most catastrophic accidental explosion in Royal Navy history — a larger loss of life than the Royal Oak, though far less famous.
• The Italian Chapel was built without any real building materials for a church: its Gothic façade is moulded from the same concrete used for the Churchill Barriers, and its "stone" interior is trompe-l'œil painting on plasterboard.
• Only two men survived the sinking of HMS Vanguard; by contrast, the drifter Daisy II saved 386 men from Royal Oak.
• The "Bull of Scapa Flow" emblem that Prien's crew painted on U-47's conning tower was later adopted as the badge of the entire 7th U-boat Flotilla.

• HMS Royal Oak — precise circumstances. The core facts (U-47 under Prien, entry via Kirk Sound at high tide on 14 October 1939, two salvoes, 835 dead) are firmly documented. But the event is heavily overlaid with dramatisation. The spy-watchmaker story is a proven myth; Prien's "autobiography" was propaganda; the concealed torpedo failures and the "impregnable base" framing are corrections the record demands. The casualty figure itself was revised from 834 to 835 only in 2019.
• The scuttling — von Reuter's knowledge. Whether von Reuter knew the Armistice had been extended to 23 June is genuinely contested between authoritative sources and should not be presented as settled.
• The "mythologisation" question. Barclay and Morris's argument that Scapa's fame has "unjustly eclipsed" the Firth of Forth is well founded as a point about public memory, but should not be read as denying Scapa's genuine primacy as the main fleet base at the times of greatest danger. The two are complementary truths, presented here evenhandedly.
• This card's scope. Card #36 is the dedicated treatment of Scapa Flow itself. It deliberately does not re-narrate Loch Ewe or the Arctic Convoys (Card #30), nor the fortification of the Firth of Forth (Card #35), except insofar as the comparative question directly bears on Scapa's significance.