Editing Scapa Flow (section)

=== Second World War ===
[[File:USS Wasp (CV-7) with other warships at Scapa Flow in April 1942.jpg|thumb|Scapa Flow in April 1942]]
[[File:The King Pays 4-day Visit To the Home Fleet. 18 To 21 March 1943, at Scapa Flow, the King, Wearing the Uniform of An Admiral of the Fleet, Paid a 4-day Visit To the Home Fleet. A15117.jpg|thumb|King [[George VI]] visiting the [[Home Fleet]] based at Scapa Flow, March 1943]]
[[File:Block Ship, Scapa Flow.jpg|thumb|[[Blockship]], Scapa Flow]]
Primarily because of its great distance from German airfields, Scapa Flow was again selected as the main British naval base during the Second World War.<ref>''The Twilight War'': Winston Churchill 1948</ref>

The strong defences built during the First World War had fallen into disrepair. Defence against air attack was inadequate and [[blockships]] sunk to stop U-boats from penetrating had largely collapsed. While there were anti-submarine nets in place over the three main entrances, they were made only of single-stranded looped wire; there was also a severe lack of the patrolling destroyers and other anti-submarine craft that had previously been available. Efforts began belatedly to repair peacetime neglect, but were not completed in time to prevent a successful penetration by enemy forces.<ref>James Miller, ''The North Atlantic Front: Orkney, Shetland, Faroe and Iceland at War'' (2004)</ref>

On 14 October 1939, under the command of [[Günther Prien]], {{GS|U-47|1938|2}} penetrated Scapa Flow and sank the First World War-era battleship {{HMS|Royal Oak|08|6}} anchored in Scapa Bay.<ref>{{cite web| url=http://www.u47.org/english/index.asp| title=U-boat U-47| publisher=u47.org| author=Rick D. Joshua| access-date=16 October 2009| archive-date=9 July 2006| archive-url=https://web.archive.org/web/20060709000402/http://u47.org/english/index.asp| url-status=live}}</ref> After firing its first torpedo salvo, the submarine turned to make its escape; but, upon realising that there was no immediate threat from surface vessels, it returned for another attack. The second torpedo salvo blew a {{convert|30|ft|m|adj=on}} hole in the ''Royal Oak'', which flooded and quickly capsized. Of the 1,400-man crew, 833 were lost. The wreck is now a protected [[war grave]].<ref>David Turner, ''Last Dawn: The Royal Oak Tragedy at Scapa Flow'' (Argyll Publishing, 2008).</ref><ref>H. J. Weaver, ''Nightmare at Scapa Flow: the truth about the sinking of HMS Royal Oak'' (Cressrelles, 1980).</ref> [[John Gunther]] in December 1939 called the attack "the single most extraordinary feat of the war so far".<ref name="gunther1940">{{cite book | url=https://archive.org/stream/in.ernet.dli.2015.149663/2015.149663.Inside-Europe#page/n19/mode/2up | title=Inside Europe | publisher=Harper & Brothers | author=Gunther, John |location=New York|author-link=John Gunther| year=1940 | pages=xxi}}</ref>

Three days after the submarine attack, four [[Luftwaffe]] [[Junkers Ju 88]] bombers of [[Kampfgeschwader 30|''Kampfgeschwader'' 1/30]] led by group commander Hauptmann Fritz Doench raided Scapa Flow on 17 October in one of the first bombing attacks on Britain during the war. The attack badly damaged an old base ship, the decommissioned battleship {{HMS|Iron Duke|1912|6}}, which was then beached at Ore Bay by a tug. One man died and 25 were injured. One of the bombers was shot down by No 1 gun of 226 Heavy Anti-Aircraft Battery on Hoy. Three of the crew died, while the radio operator Fritz Ambrosius was badly burned but managed to parachute down.<ref name="Haarr240">{{cite book|author=Geirr H. Haarr|title=The Gathering Storm: The Naval War in Northern Europe September 1939 – April 1940|url=https://books.google.com/books?id=Ft47BAAAQBAJ&pg=PA240|year=2013|publisher=Seaforth Publishing|isbn=978-1-4738-3131-5|pages=240–243|access-date=30 December 2015|archive-date=24 April 2016|archive-url=https://web.archive.org/web/20160424212230/https://books.google.com/books?id=Ft47BAAAQBAJ&pg=PA240|url-status=live}}</ref>

New blockships were sunk, booms and mines were placed over the main entrances, coast defence and anti-aircraft batteries were installed at crucial points, and [[Winston Churchill]] ordered the construction of a series of causeways to block the eastern approaches to Scapa Flow; they were built by Italian prisoners of war held in Orkney, who also built the [[Italian Chapel]]. These "[[Churchill Barriers]]" now provide road access from Mainland to Burray and South Ronaldsay, but block maritime traffic. An airfield, [[RAF Grimsetter]] (which later became HMS ''Robin''), was built and commissioned in 1940.<ref>M. Brown and P. Meehan, ''Scapa Flow: the reminiscences of men and women who served in Scapa Flow in the two World Wars'' (Allen Lane, Penguin, 1968).</ref>