Easter Sunday Raid

Last updated

Easter Sunday Raid on Ceylon
Part of the Pacific Theatre of World War II
Date5 April 1942
Location
Result Japanese victory
Belligerents
Merchant flag of Japan (1870).svg Japan
Casualties and losses
7 aircraft [1]

26 aircraft

Many more killed on the ground. [2]

The Easter Sunday Raid was an air attack on Colombo, Ceylon during the Indian Ocean raid by carrier-based aircraft of the Imperial Japanese Navy on 5 April 1942. The Japanese objective was to destroy the Ceylon-based British Eastern Fleet in harbour. The British preemptively dispersed shipping from the harbours before the attacks due to advance warning from intelligence in March 1942, and air reconnaissance during the raid.

Contents

The attacking Japanese aircraft were met by fighters of the Royal Air Force's (RAF) 222 Group, commanded by Air Vice-Marshal John D'Albiac, and the Royal Navy's Fleet Air Arm (FAA), and anti-aircraft artillery. Port facilities were damaged, and ships both in harbour and – having dispersed – on the ocean were sunk or damaged. The bulk of the British Eastern Fleet was not found and survived.

The raid demonstrated Ceylon's vulnerability; British forces were not prepared to face further Japanese carrier raids. The Eastern Fleet relocated its main base to East Africa, from which it regularly deployed carrier task forces into the central and eastern Indian Oceans.

Background

British preparations

Upon Japan's entry into the Second World War, the air defences on Ceylon consisted of only four obsolescent three-inch anti-aircraft guns at Trincomalee. The sole RAF squadron was 273 Squadron based at China Bay near Trincomalee; it flew four Vickers Vildebeest and four Fairey Seals torpedo bombers. [1] With the loss of Singapore in February 1942, British planners identified the island as essential to the defence of India and Allied lines of communication through the Indian Ocean. [3] The threat of Japanese carrier-borne air attack was recognized from the examples of Pearl Harbor in December 1941 and Darwin in February 1942. [1]

Ceylon's air defences were reinforced in early 1942. Eight Hawker Hurricane fighters arrived on 23 February; they flew in from Karachi where they had been assembled from crates delivered by Cefn-Y-Bryn. 60 Hurricanes arrived on 6 and 7 March; they were ferried by HMS Indomitable [4] from the Middle East for 30 and 261 Squadrons RAF; [5] a Hurricane from 30 Squadron was lost in a crash at sea on 4 April. On 5 April, there were 37 or 38 serviceable Hurricanes near Colombo. [4] By 4 April, there were 803 and 806 Naval Air Squadrons (NAS) from the FAA, [6] and 44 Fairey Fulmars. The number of anti-aircraft guns increased to 144 by 4 April. [7]

222 Group also received Consolidated PBY Catalina flying boats, which spotted and shadowed the Japanese fleet during the raid. The only air reinforcement to Ceylon in the two months after 7 December 1941 consisted of the first Catalina. [1] By 4 April, there were seven operational aircraft; [7] four RAF, two Royal Canadian Air Force (RCAF), and one Dutch. Two RAF and three Dutch were unserviceable, with at least some being overhauled at Bangalore. Two more RCAF aircraft arrived on 6 and 7 April after the raid started. [4] Squadrons operating Catalinas included 205 Squadron RAF and 413 Squadron RCAF. [8]

Other air reinforcements included maritime and naval strike aircraft. [7]

The airbases at Ratmalana, near Colombo, and China Bay were expanded. Another was established at the Colombo Racecourse to relieve congestion at Ratmalana. [5] The Catalinas operated from Koggala and the adjacent lagoon, near the southern tip of the island. [9] The Japanese were unaware of the bases at the Colombo Racecourse [6] and Koggala. [9]

Colombo and Trincomalee each received a radar station. [7]

The Colombo radar station unit was AMES 254. Its personnel arrived on 18 March and its equipment on 22 March. The station became operational at the Royal Colombo Golf Club – about 6 miles (9.7 km) north of Ratmalana – on 25 March, and was connected by telephone to the No. 20 Operations Room on 28 March. [10]

The station at Trincomalee was established by AMES 272. [10]

Japanese preparations

The initial IJN order authorizing the raid ("Operation C") was issued on 9 March 1942. By 16 March, the plan was to depart from Staring Bay, Celebes, on 26 March for an attack on Colombo ("C day") on 5 April; [11] these dates were honoured in the actual execution. [12]

The core of the Japanese force, commanded by Admiral Chūichi Nagumo, was five aircraft carriers; Akagi, Shōkaku and Zuikaku in Carrier Division 5, and Sōryū and Hiryū in Carrier Division 2. [13]

First moves

Japanese preparations were detected by Allied intelligence. The British defensive plan was based on assessments from the Far East Combined Bureau (FECB), which expected a "C day" of 1 April. [11] As a result, British forces at Ceylon went on alert a few days too early. The Eastern Fleet, led by Vice Admiral Sir James Somerville, sortied on 30 March and deployed in a patrol area 100 miles (160 km) south of the island. Land-based aerial reconnaissance concentrating on the southeast. The deployments accurately reflected the direction that the Japanese would approach. [14]

With no sightings of the Japanese, the Eastern Fleet retired late on 2 April toward Addu Atoll to refuel at Port T, about 600 miles (970 km) southwest of Ceylon. [14] Ships were detached to resume previous commitments; the heavy cruisers HMS Cornwall and HMS Dorsetshire were sent to Colombo, and HMS Hermes to Trincomalee. [15] Ceylon air defences stood down, but long range Catalina patrols continued. [16]

Attack on Colombo

Arrival of the Japanese fleet

Leonard Birchall piloted the Catalina that initially spotted the Japanese fleet. Leonard birchall.jpg
Leonard Birchall piloted the Catalina that initially spotted the Japanese fleet.

The Japanese cancelled a planned reconnaissance of Colombo harbour on 4 April by cruiser floatplanes. [17]

Before dawn on 4 April, Catalina QL-A of 413 Squadron RCAF, piloted by Squadron Leader Leonard Birchall, took off from Koggala to patrol the southernmost patrol sector. Later that day, the crew decided to repeat an assigned leg that took them to the southern-most point of their patrol; the repetition was conducted for navigational purposes. [18] At 16:00, at the southern-most point of the repeated leg, QL-A spotted the Japanese fleet on the southern horizon about 360  mi (310  nmi ; 580  km ) south-east of Ceylon. [19] [8] [14] The flying boat was attacked by at least 12 Mitsubishi A6M Zero fighters as it closed to get an accurate sighting. The radio was destroyed mid-transmission [19] so that the sighting, but not the size of the fleet, was reported. [14] Within seven minutes, QL-A was forced to make an emergency landing on the ocean. Strafing Zeroes sank the flying boat and killed two crew members in the water. Only six of the nine crew, including Birchall, survived to be captured by the Japanese destroyer Isokaze . [19] The prisoners claimed to have taken off from Colombo instead of Koggala, [9] and this was reported to the fleet flagship Akagi late on 4 April; [20] Koggala was not struck during the raid. [9] The prisoners also denied making any reports; this was undermined when the Japanese intercepted a signal from Colombo asking QL-A to repeat its report, indicating that surprise was lost. [19]

Catalina FV-R from 205 Squadron RAF, piloted by Flight Lieutenant "Jock" Graham, took off at 17:45 and took over shadowing the Japanese fleet. FV-R made reports at 22:37, and on 5 April at 00:45 and 06:15. The last reported Japanese ships 110 miles (180 km) and 195 degrees from Dondra Head, the southern tip of Ceylon. The Catalina was shot down by Japanese fighters about 90 minutes after making the final report, with the loss of the entire crew. [8]

Within an hour of QL-A's report, D’Albiac met with his subordinates to discuss an anticipated Japanese strike after dawn. 222 Group issued Operation Order No. 43 before midnight to warn subordinate units, and units went on alert at 04:00 on 5 April. [8] [21] Per Operation Order No. 43, 803 NAS launched a six Fulmars from Ratmalana early on 5 April to conduct a line patrol from Bentota, 35 mi (56 km) south of Colombo on the west coast, to Pottuvri on the east coast. [22] Ships were ordered to disperse from the harbours at Colombo and Trincomalee. Cornwall and Dorsetshire left Colombo late on 4 April to rejoin the Eastern Fleet, [23] part of which had started sailing back to Ceylon from Port T after the QL-A report. [15]

At 05:45 on 5 April, Catalina BN-L of 240 Squadron RAF, piloted by Flight Lieutenant Bradshaw, took off to shadow the Japanese fleet. [21]

Failure of British early warning

Mitsubishi A6M Zero fighters escorted the attacking bombers. Zero Akagi Dec1941.jpg
Mitsubishi A6M Zero fighters escorted the attacking bombers.

The Japanese carriers began flying off 91 bombers and 36 fighters for the strike on Colombo [24] shortly after 06:00 on 5 April. [25]

Shortly after 06:40, Catalina BN-L spotted four Japanese aircraft flying north but misidentified them as Hurricanes and made no report. The flying boat was seen by the Japanese; Hiryu received a report of the encounter at 06:45. [21] The strike group approached Colombo from the sea to the south-east; [7] [21] this course prevented detection by coast watchers and the 803 NAS line patrol. [22] AMES 254 and its radar also failed to detect or report the inbound strike. [26]

British fighter pilots waited for a scramble order that, due to the lack of early warning, never came. Instead they were forced take-off under fire, instead of starting the engagement pre-positioned in the air. [27]

The attack

RAF Hawker Hurricanes made up the bulk of the defending fighters. RAF Hurricane.jpg
RAF Hawker Hurricanes made up the bulk of the defending fighters.

At 07:30, an advance force of nine Zero fighters from Hiryu flew over the Colombo Racecourse airbase and were spotted from the ground. The 14 Hurricanes of 258 Squadron RAF took off in good order by 07:35 and climbed toward the harbour. The airbase avoided attack. [6]

At 07:40, 38 Aichi D3A "Val" bombers from Shokaku and Zuikaku were spotted from Ratmalana. 14 from Zuikaku attacked the airbase at 07:45 as Hurricanes from 30 Squadron RAF were taking off in ones and twos. 21 Hurricanes took off (four were still on the ground when the first bombs fell) and another – the commanding officer's – was disabled attempting to take-off. Six Fulmars from 803 and 806 NAS also took off from Ratmalana. These British fighters were fully occupied defending the airbase, and were aided by heavy cloud cover. The first Hurricanes airborne attacked the bombers before any bombs were dropped. Five Vals and a Zero were destroyed, and up to six more Vals were damaged. In exchange, eight Hurricanes and three Fulmars were shot down. The airbase suffered little damage. [6]

19 Vals from Shokaku attacked the harbour around 07:50; they ultimately sank the armed merchant cruiser HMS Hector and damaged the submarine depot ship Lucia. They were set upon by 258 Squadron RAF shortly afterwards, [9] which decided to concentrate on bombers rather than the covering Zeros. [6] One Val was shot down, and damaged another, in exchange for eight Hurricanes destroyed and two badly damaged. [9]

The Shokaku Vals fully occupied 258 Squadron RAF, allowing the remaining bombers to attack the harbour and port unimpeded by British fighters. [9] Five Vals from Zuikaku damaged the British tanker San Cirilo. 53 Nakajima B5N "Kate" torpedo bombers, acting as level bombers, sank the old destroyer HMS Tenedos, damaged the merchant ship Benledi, and hit port facilities. [9]

In addition, the Norwegian tanker Soli was sunk and the British freighter Clan Murdoch was damaged. [20]

The Japanese strike was recovered by their carriers from 09:45 to 10:30. [13]

Second strike cancelled

Carrier Division 5 reserve strike force was armed with high explosive bombs for a second strike on Colombo. This was cancelled when Japanese scout aircraft discovered Dorsetshire and Cornwall at 10:00 on 5 April. Carrier Division 5 reserve strike force was ordered to attack the British cruisers, but rearming with torpedoes encountered delays, and the cruisers were sunk by Carrier Division 2 instead. [28]

Aftermath

British aircraft losses

30 Squadron RAF had seven serviceable aircraft by nightfall. Eight Hurricanes had been shot down, and several damaged. Five pilots were killed and two wounded. [6]

258 Squadron RAF suffered eight Hurricanes shot down and two badly damaged, as well as five pilots killed and two wounded. [9]

803 and 806 NAS suffered four Fulmars shot down and three pilots killed. [6]

Six Fairey Swordfish from 788 Naval Air Squadron were also shot down; they were transferring from China Bay to Colombo for a strike on the Japanese fleet and arrived during the attack. [6]

Radar

According to AMES 254's logs, its radar was operational during the battle and it did not detect the incoming strike. [10] Official post-war technical histories attributed the failure to technical limitations of the radar, [10] and operator error caused by fatigue due to "unequally divided watch-keeping roster." [29]

The short time that AMES 254 had been in Colombo may not have been sufficient to train operators to identify false radar echoes produced by local conditions; real echoes may have been mistaken for false echoes [10] Additionally, the radar antenna projected "lobes" in which objects might be detected, with gaps between lobes or lobes overlapping. The height of an object heavily affected detection range. The trajectory of the incoming Japanese aircraft may have inadvertently taken advantage in gaps between lobes. [29]

AMES 254 may simply not have had enough time to process the radar data, especially if operator fatigue was a factor. [29] The terrain around the radar limited maximum range to 60 mi (97 km). The distance travelled by Japanese aircraft between the edge of that radius to Ratmalana was 54 mi (87 km), and could be covered by a Zero at cruise speed in about 17 minutes. During the battle it took five minutes for the Hurricanes to take off and another six to climb to interception altitude. This left only six minutes for AMES 254 to report to No. 20 Operations Room and for orders to be issued to pilots. [10]

Awards

Birchall was awarded the Distinguished Flying Cross for the sighting made by Catalina QL-A on 4 April, [30] and was called the "Saviour of Ceylon" by Canadian media. He was a prisoner of war for the remainder of the war. [31]

British Commonwealth units in Ceylon at the time of the attack

Ground

Ceylonese units

Commonwealth units

Air

Royal Air Force

Fleet Air Arm

See also

Related Research Articles

HMS <i>Hermes</i> (95) 1924 unique aircraft carrier

HMS Hermes was a British aircraft carrier built for the Royal Navy and was the world's first ship to be designed as an aircraft carrier, although the Imperial Japanese Navy's Hōshō was the first to be commissioned. The ship's construction began during the First World War, but she was not completed until after the end of the war, having been delayed by multiple changes in her design after she was laid down. After she was launched, the Armstrong Whitworth shipyard which built her closed, and her fitting out was suspended. Most of the changes made were to optimise her design, in light of the results of experiments with operational carriers.

HMS <i>Victorious</i> (R38) 1941 Illustrious-class aircraft carrier of the Royal Navy

HMS Victorious was the third Illustrious-class aircraft carrier after Illustrious and Formidable. Ordered under the 1936 Naval Programme, she was laid down at the Vickers-Armstrong shipyard at Newcastle upon Tyne in 1937 and launched two years later in 1939. Her commissioning was delayed until 1941 due to the greater need for escort vessels for service in the Battle of the Atlantic.

HMS <i>Illustrious</i> (87) 1940 Illustrious-class aircraft carrier of the Royal Navy

HMS Illustrious was the lead ship of her class of aircraft carriers built for the Royal Navy before World War II. Her first assignment after completion and working up was with the Mediterranean Fleet, in which her aircraft's most notable achievement was sinking one Italian battleship and badly damaging two others during the Battle of Taranto in late 1940. Two months later the carrier was crippled by German dive bombers and was repaired in the United States. After sustaining damage on the voyage home in late 1941 by a collision with her sister ship Formidable, Illustrious was sent to the Indian Ocean in early 1942 to support the invasion of Vichy French Madagascar. After returning home in early 1943, the ship was given a lengthy refit and briefly assigned to the Home Fleet. She was transferred to Force H for the Battle of Salerno in mid-1943 and then rejoined the Eastern Fleet in the Indian Ocean at the beginning of 1944. Her aircraft attacked several targets in the Japanese-occupied Dutch East Indies over the following year before Illustrious was transferred to the newly formed British Pacific Fleet (BPF). The carrier participated in the early stages of the Battle of Okinawa until mechanical defects arising from accumulated battle damage became so severe she was ordered home early for repairs in May 1945.

<span class="mw-page-title-main">Fairey Fulmar</span> British carrier-borne reconnaissance aircraft/fighter aircraft

The Fairey Fulmar is a British carrier-borne reconnaissance aircraft/fighter aircraft which was developed and manufactured by aircraft company Fairey Aviation. It was named after the northern fulmar, a seabird native to the British Isles. The Fulmar served with the Royal Navy's Fleet Air Arm (FAA) during the Second World War.

<span class="mw-page-title-main">Leonard Birchall</span>

Air Commodore Leonard Joseph Birchall,, "The Saviour of Ceylon", was a Royal Canadian Air Force (RCAF) officer who warned of a Japanese attack on the island of Ceylon during the Second World War.

<span class="mw-page-title-main">Indian Ocean raid</span> 1942 raid of Allied shipping by the Imperial Japanese Navy

The Indian Ocean raid, also known as Operation C or Battle of Ceylon in Japanese, was a naval sortie carried out by the Imperial Japanese Navy (IJN) from 31 March to 10 April 1942. Japanese aircraft carriers under Admiral Chūichi Nagumo struck Allied shipping and naval bases around British Ceylon, but failed to locate and destroy the bulk of the British Eastern Fleet. The Eastern Fleet, commanded by Admiral Sir James Somerville, was forewarned by intelligence and sailed from its bases prior to the raid; its attempt to attack the Japanese was frustrated by poor tactical intelligence.

Ratmalana International Airport, is the secondary international airport serving the city of Colombo, the capital of Sri Lanka. It was the country's first international airport and was the only international airport in Sri Lanka until the inauguration of Bandaranaike International Airport, Katunayake, in 1967. The airport currently serves several domestic services and is home to several aviation training organisations. A relaxation of rules has recently seen the airport open for international corporate jet operations and charter flights. The airport is located 15 km south of Colombo City.

After the outbreak of the Second World War, in the British Crown Colony of Ceylon, the government of Sir Don Baron Jayatilaka assured the British King and his government of its continued support.

<span class="mw-page-title-main">Geoffrey Layton</span> British Royal Navy officer (1884-1964)

Admiral Sir Geoffrey Layton, was a Royal Navy officer. He was in command of the submarine HMS E13 when, under attack from German vessels, it ran aground off the Danish coast during the First World War. Despite this incident, he rose to senior command in the Second World War and retired in 1947. His final appointment had been as Commander-in-Chief, Portsmouth.

<span class="mw-page-title-main">China Bay Airport</span> Airport in China Bay, Sri Lanka

China Bay Airport is an air force base and domestic airport in China Bay in eastern Sri Lanka. Located approximately 7 km (4.3 mi) south west of the city of Trincomalee, the airport is also known as Trincomalee Airport and SLAF China Bay.

<span class="mw-page-title-main">No. 205 Squadron RAF</span> Defunct flying squadron of the Royal Air Force

No. 205 Squadron was a Royal Air Force unit formed on 1 April 1918. Prior to this it had existed as No. 5 Squadron of the Royal Naval Air Service (RNAS). In 1929, it became the first RAF squadron to be permanently based in Singapore, taking as its motto Pertama di Malaya. No. 205 Squadron operated during the Second World War and the Cold War before disbanding on 31 October 1971.

<span class="mw-page-title-main">803 Naval Air Squadron</span> Military unit

803 Naval Air Squadron was a Royal Navy Fleet Air Arm squadron.

806 Naval Air Squadron was a fighter squadron in the Fleet Air Arm that existed from February 1940 to December 1960 and saw active service in the Norwegian campaign, the Dunkirk evacuation and the Malta Convoys.

<span class="mw-page-title-main">No. 222 Group RAF</span> Former Royal Air Force operations group

No. 222 Group was a group of the Royal Air Force during the Second World War. Formed on 1 September 1941, based at Ceylon. Squadrons were stationed around the Indian Ocean. The group undertook long-range bombing and mine-laying operations that took them as far afield as Sumatra and Singapore.

Sri Lanka Navy (SLN) Dockyard is the largest naval base of the Sri Lanka Navy and a major shipyard located in Trincomalee, Sri Lanka. Established by the British as the Royal Naval Dockyard, Trincomalee, it was home to the East Indies Station of the Royal Navy during World War II. Since the withdrawal of the Royal Navy, the Royal Ceylon Navy took over the dockyard. It became the home base of the RCyN fleet, and today it is home to the Eastern Naval Command and the Naval and Maritime Academy of the Sri Lanka Navy.

<span class="mw-page-title-main">Colombo Racecourse</span> Sports venue in Colombo, Sri Lanka

Colombo Racecourse is a historical harness racing course in the Cinnamon Gardens, Colombo. During the Second World War, it was used as a temporary airfield. In 2012, it was redeveloped as the Colombo Racecourse Sports Complex to become the first International Rugby Union ground in Sri Lanka to host all the national rugby union side's home matches.

<span class="mw-page-title-main">733 Naval Air Squadron</span> Royal Navy Fleet Air Arm Squadron

733 Naval Air Squadron was a Naval Air Squadron of the Royal Navy's Fleet Air Arm. It was active between January 1944 and December 1947, entirely in Ceylon, as a Fleet Requirements Unit, based mainly at R.N. Air Section China Bay, which became HMS Bambara, RNAS Trincomalee, China Bay, Ceylon. The squadron initially formed at R.N. Air Section Minneriya, at RAF Minnerya, Ceylon, two weeks after an advance party arrived there, remaining for three months after formation before relocating.

<span class="mw-page-title-main">742 Naval Air Squadron</span> Royal Navy Fleet Air Arm Squadron

742 Naval Air Squadron was a Naval Air Squadron of the Royal Navy's Fleet Air Arm which disbanded during August 1946. It was active initially from the end of 1943 as a Communications Squadron operating in Sri Lanka and India. It later became a Royal Navy Air Transport Squadron, covering the same geography.

<span class="mw-page-title-main">788 Naval Air Squadron</span> Royal Navy Fleet Air Arm Squadron

788 Naval Air Squadron was a Naval Air Squadron of the Royal Navy's Fleet Air Arm which last disbanded during June 1945. The squadron formed at RN Air Section China Bay in Ceylon, in January 1942, as the British Eastern Fleet's Torpedo Bomber Reconnaissance Pool, however it lost half its strength during the heavy raids by Japanese carrier-borne aircraft in the April. The squadron regrouped at RNAS Tanga in Tanganyika, East Africa to become a Fleet Requirements Unit and relocating almost immediately to RN Air Section Port Reitz, in Mombasa, where it remained operational for the next three years.

<span class="mw-page-title-main">1844 Naval Air Squadron</span> Royal Navy Fleet Air Arm and Reserve Air Squadron

1844 Naval Air Squadron was a Naval Air Squadron of the Royal Navy's Fleet Air Arm between 1943 and 1945 and then a Royal Naval Volunteer Reserve Air Squadron from 1954 to 1957. It formed in Northern Ireland at HMS Gannet, RNAS Eglinton, in December 1943, as a fighter squadron. It embarked in HMS Begum, in February 1944, for the Far East, arriving in Ceylon, in June and joining HMS Indomitable the following month. August, September and October saw the squadron undertake photographic reconnaissance and provide fighter cover for the attacks on Indaroeng and Emmahaven in Sumatra, then on Sigli, followed by the Nicobar Islands respectively.

References

Citations

  1. 1 2 3 4 Stuart 2014, p. 33
  2. "Ceylon's Pearl Harbour attack". www.sundaytimes.lk. Retrieved 19 May 2017.
  3. Boyd, pp. 364–359
  4. 1 2 3 Stuart 2014, p. 44
  5. 1 2 Richards, Denis; Saunders, Hilary St. George (1954). The Fight Avails. Official History of the Royal Air Force 1935–1945. Vol. 2. London: Her Majesty's Stationery Office. Chapter IV – Burma Falls. (reprinted by Pickle Partners Publishing, 2013; ebook)
  6. 1 2 3 4 5 6 7 8 Stuart 2014, p. 42
  7. 1 2 3 4 5 Stuart 2014, p. 35
  8. 1 2 3 4 Stuart 2014, p. 37
  9. 1 2 3 4 5 6 7 8 9 Stuart 2014, p. 43
  10. 1 2 3 4 5 6 Stuart 2014, p. 40
  11. 1 2 Boyd, p. 366
  12. Boyd, p. 367
  13. 1 2 Boyd, p. 373
  14. 1 2 3 4 Boyd, p. 368
  15. 1 2 Boyd, p. 370
  16. Stuart 2014, p. 36
  17. Boyd, p. 369
  18. Stuart 2006, p. 68
  19. 1 2 3 4 Stuart 2006, p. 69
  20. 1 2 Stuart 2014, p. 47
  21. 1 2 3 4 Stuart 2014, p. 38
  22. 1 2 Stuart 2014, p. 39
  23. Roskill, p. 27
  24. Roskill, p. 26
  25. Boyd, p. 371
  26. Stuart 2014, pp. 39–41
  27. Stuart 2014, pp. 42–44
  28. Boyd, p. 372
  29. 1 2 3 Stuart 2014, p. 41
  30. Stuart 2014, p. 45
  31. Stuart 2006, p. 73

Sources