Torpedo

Occasional Paper 101: RAN Torpedo Factory, Neutral Bay

February 4, 2021

By Midshipman Lloyd Skinner, RAN

In 1942, the Royal Australian Navy (RAN) Torpedo Factory, located at Neutral Bay, Sydney commenced operations. Previously, the Torpedo Depot at Garden Island across the Harbour had been the main site responsible for managing torpedo maintenance and storage. Additionally, a torpedo range established at Pittwater in Northern Sydney had responsibility for testing torpedoes from late 1943.

On 22 December 1941 the War Cabinet decided that torpedoes would be manufactured on Australian shores. This decision reflected an expansion of precision mechanical engineering across Australia throughout the Second World War. Historian Stuart Macintyre asserts that Australia was “unable to produce a motor in 1939 yet by 1945 it was manufacturing the most advanced four-engine aircraft.”

Implementation of the Government direction was swift with the Business Board seeking to economize by acquiring an existing industrial facility as the preferred option. Thus, the site chosen for the RAN Torpedo Factory was the defunct North Sydney Gasworks site at Neutral Bay, Sydney.

The RAN acquired the assistance of Mr Essington Lewis, who directed the Department of Munitions during the Second World War and was a managing director at BHP. It was Lewis’ decision to demolish the entire existing infrastructure in Neutral Bay. In keeping with wartime pace, Lewis instigated a meeting at his Melbourne office on Friday and by the evening a contract was signed in which a contractor would begin renovations on the coming Monday. As of February 1943, the RAN Torpedo Factory, in outstandingly short time, had been completed. The factory employed specialist turners and fitters, many from Garden Island who constructed torpedoes with parts acquired from the United States and South Australia.

Two hundred women were also recruited to work in the Torpedo Factory. They filled roles such as machinists and performed detailed work. The employment of women in munitions and factory work represents a growth of women in the workforce during World War Two. In January 1942, the Manpower Directorate had been established with the intention of sanctioning the transfer of workers from non-essential sectors to industries that would directly assist the war effort. As a result, many women, both voluntarily and compulsorily, entered the workforce. Women, in unprecedented numbers were employed in what was contemporarily called ‘men’s work,’ particularly in manufacturing munitions. In 1939, women accounted for just 10% of the munitions workforce, yet by 1943 women constituted 50% of this profession.

Pier at Torpedo Range in Pittwater, Broken Bay, 30 miles North of Sydney.

Women were also involved in testing of torpedoes at the Pittwater Firing Range. The range was initially surveyed by the RAN Hydrographic Branch. Then followed construction of observation stations, workshops, a pier, target rafts and firing tubes. The first torpedo was ranged on 24 February 1944 when Range Officer, Lieutenant Owens stated that “the performance of this torpedo could not be bettered.” Every torpedo would be tested on the range twice before its deployment on a submarine or warship.

The establishment and operation of the torpedo facility and range is demonstrative of how Australia’s wartime needs culminated in efficient and rapid actions to fill gaps in the nation’s warfighting capability. While the wartime conditions spurred on quick actions to establish and operate the facility, there were minimal short cuts and compromises in the production of munitions by the Torpedo factory and testing processes on the Pittwater range.

Further Reading:

Robert Curran, RAN Torpedo Factory Neutral Bay, RAN Armament Depots Website available at http://users.tpg.com.au/borclaud/ranad/about_rantf.html

Occasional Paper 13: Local Australian/USA Submarine Initiative Helps Turn the Tide of War Against Japan in 1942

August 1, 2017

August 2017

The following story provided by Commodore Bob Trotter OAM RAN (Ret’d), National President of the Submarine Association is about a little-known part of the shared Australia/USA submarine history which helped turn the tide of war in the Pacific.

Tuesday 20th June 2017 was the 75th Anniversary of events in Albany that turned the tide of the Pacific War.

History records that from March 1942 Allied Submarines had retreated to Fremantle and Albany via Surabaya & Tjilatjap in Java, Darwin and Exmouth, and, from bases there conducted some 170 submarine operations with a profound effect on the outcome of the war. Not well known is that from the start of the Pacific War, US submarines had very few successes against enemy shipping despite aggressive patrolling of enemy invasion and re-supply routes in the Philippines and Dutch East Indies theatres. The main reason appeared to be the submarine’s main offensive weapon, the Mk 14 torpedo.

By May of 1942, Commander Submarines Southwest Pacific, Captain Charles Lockwood USN then Headquartered in the long since demolished CML Building in Perth, had received report after report of perfectly aimed torpedoes passing harmlessly beneath target ships. These complaints had barely disturbed the calm of the Bureau of Ordnance which had countered by asserting that claims of problem torpedoes were inventions to disguise the performance shortcomings of submarine skippers. Incensed by this and impressed by the detailed reports and analyses by the submarine skippers, the experienced Lockwood was spurred into action and, like in many wartime cases, the initiative of the ‘men at the front’ came to the fore by ignoring red tape, rolling up their sleeves and forcing a solution.

Supervised by Lockwood’s Chief of Staff, Captain James Fife USN, on 20th and 21st June 1942 Lieutenant Commander James ‘Red’ Coe in USS Skipjack fired three test torpedoes through a fishing net strung across Frenchman’s Bay at Albany. The tests concluded that the torpedoes were running on average 11 feet deeper than that set. In combat this would mean that the torpedoes were too far beneath the target’s hull for the fuse to operate correctly, resulting in them passing under without exploding. Maintaining its scepticism, the Bureau of Ordnance discredited the tests and suggested that Lockwood should conserve his scarce supply of torpedoes.

Undaunted, Lockwood organised another test and on 18th July USS Saury fired five torpedoes at the net, all of which ran deep. The Bureau of Ordnance was finally driven to conducting its own tests on 1st August 1942 which, unsurprisingly to the skippers, concluded that the Mk 14 Torpedo ran 10 feet deeper that set. After a thorough investigation, the Bureau uncovered a series of design defects and testing deficiencies that caused the deep running.

The depth setting mechanism was completely re-designed and following extensive testing the submarines operations were conducted with increased confidence.

From a start point of very limited success in 1942, by mid-1945 virtually all the Japanese merchant fleet and most of its Navy had been sunk, starving the Japanese of the resources it needed to continue the war and to feed its people.

‘Red’ Coe’s April/May 1942 Report of his patrol off Indo China included the statement:
“To make a round trip of 8,500 miles into enemy waters, to gain an attack position undetected within 800 yards enemy ships only to find that the torpedoes run deep and over half the time will fail to explode, seems to me to be an undesirable manner of gaining information which might be determined any morning within a few miles of a torpedo station in the presence of comparatively few hazards.”

A few hours, a single submarine, a fishing net, and a few torpedoes at Frenchman’s Bay Albany had proved Coe and the other skippers right and changed the course of the war in the Pacific.

Louis Brennan (1852-1932) – the Wizard of Oz

June 24, 2014

By Mike Turner

Louis Brennan was a brilliant and prolific inventor. Two of his best known inventions were a gyro-stabilised train for a monorail and a type of helicopter, but by far his most important invention was a torpedo that was the world’s first practical guided missile. Although Brennan spent most of his life in England he was educated in Melbourne where he commenced the development of his torpedo with technical assistance from the University of Melbourne as well as financial backing by Melbourne businessmen and the Victorian Government.

circa 1885: Louis Brennan (1852 – 1932), inventor of the dirigible torpedo. (Photo by Hulton Archive/Getty Images)

Louis Philip Brennan was born on 28 January 1852 at Castlebar, County Mayo, Ireland. He was the tenth child of Thomas Brennan, a hardware merchant, and his wife Honor (nee McDonnell). His elder brother Patrick John went to Australia in 1856 and became a teacher in Melbourne. In 1861 Louis, then aged 9, emigrated from Ireland with his parents to the gold rush boomtown of Melbourne. Louis had a keen interest in how all his mechanical toys worked, and experimented on extending their use and efficiency. He became an excellent student at evening classes at the Collingwood School for Design, founded by a prominent public figure Joel Eade in 1871 for ‘rising operatives’.¹ In 1873 at Melbourne’s Juvenile Industries Exhibition Brennan showed some of his work, such as a window safety latch, a mincing machine and a billiard marker adopted by manufacturers Alcock & Company.

Louis was apprenticed to Alexander Kennedy Smith, a wealthy Scotsman who ran the biggest foundry in Melbourne. Smith was a renowned civil and mechanical engineer and encouraged Brennan. Smith was also a Major in the Victoria Volunteer Artillery Regiment, a sister branch to the Victoria Torpedo Corps, and this was to prove invaluable for the inventor of a torpedo.² Smith was Melbourne’s Lord Mayor in 1875-1876 and a member of the Victorian Legislative Assembly from1877 to1881.

Brennan was associated with printer William Calvert in designs for a number of inventive devices, including an incubator and a mini lift for stairs, and in 1872 jointly registered patents for an improved weighing machine.³ He held at least 38 patents in very diverse fields.

In 1874, with advice and encouragement from William Charles Kernot, lecturer (and later Professor of Engineering) at the University of Melbourne, at age 22 Brennan commenced the development of a wire guided torpedo. Kernot performed numerous calculations, and was later paid £500 by Brennan in recognition of past assistance. Brennan and Calvert registered patents for the torpedo, and British Patent No. 3359 was granted on 4 September 1877. In the state’s legislature on 2 October 1877 A.K. Smith raised the matter of a grant to the company and £700 was received from the Victorian Government.⁴ Shortly afterwards the Brennan Torpedo Company was formed with Melbourne businessmen John Temperley and Charles and Edwin Millar to promote the torpedo commercially.

A public demonstration was conducted in Hobsons Bay, Melbourne in 1879, witnessed by various senior Navy and Army officers. A small target boat was hit at a range of 370 meters and the observers were impressed. A favourable report was sent to the Admiralty in 1879 by Rear Admiral J. Wilson RN, Commodore Royal Navy Australian Squadron.⁵ In 1881, on the invitation of the Admiralty, Brennan and Temperley went to England with the torpedo and it was examined at HMS Vernon. The Admiralty refused to bear the cost of future trials since they felt that the torpedo was unsuitable for use from ships. So Brennan and Temperley approached the War Department. The War Department showed interest and the Admiralty arranged an inspection on 23 June 1881 by Lieutenant Colonel Lyon, Royal Artillery and RN officers. Although the Admiralty was not directly interested in the torpedo it agreed to assist in trials by the Royal Engineers with a view to coastal defence. A favourable trials report prepared by a Royal Engineers committee in May 1882 recommended that further trials be conducted at the expense of the British Government.

Brennan and Temperley continued the development of the torpedo. They were assisted by the Royal Engineers and used workshops at Brompton Barracks, Chatham. In 1893 Brennan proclaimed that the torpedo was ready for testing, and Garrison Point Fort, Sheerness was selected as the trials site. On 13 March 1893 Brennan was given £3,000 to cover his expenses to date and put on an annual salary of £1,000 for three years or until two months after notification of the fitness for trial of the torpedo. Following a trial on 26 October 1886 the Admiralty declared that the torpedo was unsuitable for the Royal Navy but was very desirable for coastal defence using shore launching. The War Office recognised the value of the torpedo for coastal defence and negotiated an agreement agreed by Parliament on 10 March 1887. The payment of £110,000 was a vast sum (about 20 million in current Australian dollars), but it provided the War Office with exclusive use of the torpedo. A factory for torpedoes and associated equipment, the Government Torpedo Manufacturing Plant, was set up at Gillingham with Brennan as Superintendent and Temperley as his assistant. Brennan was to receive £1,500 per annum and Temperley £1,200 per annum. Further development of the torpedo was undertaken whilst shore stations for coastal defence were being installed, the last shore station being completed in November 1894.

Replica Brennan torpedo. Hong Kong Museum of Coastal Defence

Prototype monorail car on a demonstration run. Science Museum, London.

In May 1892 Brennan was awarded a Companion of the Order of the Bath (CB) for his work on the torpedo. Louis married Anna Mary Quinn, also a native of Castlebar, in Dublin on 10 September 1892. They lived in Gillingham overlooking the River Medway. He had an incredibly fertile brain and frequently had ideas during the night. He avoided disturbing his wife by inventing the ‘Brennanograph’, a silent five-key typewriter similar to those used by stenographers in law courts. He was replaced by a Royal Engineer Officer as Superintendent in 1895, but was retained as a consultant until 1907.

Able to turn his mind to other matters and using money he had acquired from his torpedo, he invented a monorail train stabilised by a gyroscope and devoted twelve years to its development. He persuaded the War Department to let him use the vacant torpedo factory for development. The 20 tonne prototype carriage was propelled by a 60 kW petrol engine, and a 15 kW petrol engine drove two electric motors for two gyroscopes.⁶ Brennan envisaged a train of six carriages travelling at 330 kph, each carriage with its own gyro stabilisers which, inter alia, enabled a carriage to lean into a bend in the monorail. Sir Winston Churchill actively supported it and saw it as an invention which promised to revolutionise the railway systems of the world. Churchill bullied the India Office into giving Brennan a secret grant of £5,000. Using gyro stabilisation the monorail could traverse a chasm on a single steel cable, and the press dubbed the monorail the ‘Blondin railway’ after the famous tightrope walker. The Maharajah of Kashmir was convinced that the monorail would be the ideal way to traverse Himalayan foothills and he also gave Brennan a grant of £5,000. It won the highest award at the Japan-British Exhibition in 1910. But there was to be no more development after the prototype stage, apparently due to concern that the gyros might fail. Brennan had spent so much money on the monorail that he was forced to sell his home and return to work.

After being employed with the Ministry of Munitions from 1910 to 1918 he moved to the Royal Aircraft Factory at Farnborough where he worked from 1919 to 1926 on a type of helicopter. It had an empty weight of 1,360 kg and had a single 18 m rotor.⁷ Propellers at the rotor tips produced torqueless rotation and a tail rotor was not required. Power was by a Bentley BR-2 170 kW rotary driving transmission shafts that ran down the length of the blades. It could hover successfully but proved difficult to handle in forward flight. The helicopter project was cancelled in February 1926 after the helicopter crashed, and official interest turned to the Clierva type autogyro. Brennan was devastated but continued with development as a private venture and it eventually drained his finances.

Brennan’s private life was in stark contrast to his brilliant career. At least five of his ten siblings died as small children in the 1840s during the Irish Famine. One of his two daughters died in the flu epidemic that followed the First World War.⁸ His wife died in 1931, and Brennan was knocked down by a motorcar on 26 December 1931 whist holidaying in Montreux, Switzerland. He died there from his injuries on 17 January 1932, and was survived by an only son and a daughter. His son, Captain Michael Brennan, RE, had a distinguished war record during World War I and died on 21 November 1933, less than two years after his father.

The Brennan Torpedo

Germany is generally credited with the first practicable guided weapon, the aircraft radio controlled Ruhrstahl SD 1400 (‘Fritz X’) guide bomb which entered service in 1943.⁹ It is not generally known that the first practical guided weapon was a wire guided torpedo designed in Australia by Brennan and patented in 1877.

The Brennan torpedo was similar in size to current submarine launched torpedoes such as the American Mark 48 in RAN submarines. It was much larger that the contemporary Mark 3 Whitehead torpedo which had a weight of 384 kg and a length of 3.6 m.¹⁰ Data on speed and range is conflicting. The maximum range is generally reported as 1,800 m, but appears to refer to the length of wire. Analysis of torpedo motion shows the range to be the length of wire reduced by two significant factors, one the propeller efficiency and the other depending on torpedo hydrodynamic drag and wire tension. The following speed and ranges are best estimates.

Weight: 1 tonne (approx.)

Length: 6.4 m

Cross section: Oval, 68 x 53 cm

Warhead: 100 kg guncotton

Maximum speed: 27 knots for 900 m

Maximum range: At least 1100 m

The main charge was 100 kg of wet guncotton initiated by a dry guncotton primer and a 77 grain Mark III torpedo detonator fired by an inertia pistol. The main charge had to be kept wet to prevent spontaneous detonation. The main charge chamber was regularly weighed to ensure that the guncotton had not dried out. Carbolic solution was added to restore the weight to the required value if the weight of the chamber decreased by more than two percent below the required value.

In contact with a hull the main charge was large enough to sink even the largest warships in service circa 1900. During the Russo-Japanese war of 1904-1905 the Russians laid their Model 1898 moored contact mine which had a main charge of only 56 kg of guncotton.¹¹ Despite the small main charge the Japanese lost two battleships.¹²

Torpedo propulsion and guidance by two wires

The Brennan torpedo had two contra-rotating propellers powered by two shafts, one shaft surrounding the other. The forward propeller was powered by the outer shaft, and the aft propeller by the inner shaft. Each shaft was independently powered by its own wire drum containing 1,800 m of 1.8 mm diameter wire. Both wires were unwound by a shore station winch, and wire tension provided propeller shaft torque. The propellers acted like tug propellers and the total propeller thrust exceeded torpedo hydrodynamic drag by a ‘tow load’ equal to the total wire tension, generally 4 kN (400 kg). Depth was controlled by the forward planes driven by a servo mechanism in the ‘depth mechanism’. Depth input for the servo mechanism was measured by a hydrostatic valve in the nose.

The wire guidance used by Brennan is not to be confused with the wire guidance used by modern submarine torpedoes. Currently ‘wire’ refers to a thin electric cable trailed by the torpedo to the launching submarine.

As shown in Figure 1, each wire is unwound from its drum and passes around a reciprocating pulley travelling fore and aft in synchronisation with drum rotation. The two wires run around two pulleys known as ‘steering drive pulleys’, then inside the aft propeller shaft before leaving the torpedo. When a shore station made the wire speeds at the torpedo different the two steering drive pulleys rotated at different speeds. The difference in pulley speeds was the input to the steering mechanism which (by some unknown means) operated the four rudders, two at the bow and two at the stern.¹³ There was a 12 volt light at the top of a mast to assist the shore station steer the torpedo, and this light was only visible from astern.

Steering a torpedo

There were various versions of the ingenious system used in shore stations to guide the torpedo, and the data in this paper is for the final version. The shore station winch was driven by a steam engine of about 190 kW. The winch had a separating plate on its drum, and the two wires were wound onto their half of the drum at the same wire speed. Wire tension was automatically controlled by a hydraulic governor and recorded by a dynamometer. Torpedo speed and range could be varied by varying the wire tension.

Each wire passed around a steering pulley that could be moved along each side of a horizontal steering girder above the winch, and these two pulleys were initially side-by-side above the winch drum. Whilst the steering wheel was being turned the two steering pulleys moved at the same speed v in opposite directions along a horizontal beam, the steering pulley speed depending on the steering wheel speed of rotation. The difference in wire speeds was four times the steering pulley speed, Figure 2 refers. When the helmsman stopped turning the steering wheel the wire speeds at the torpedo reverted to the same speed and the torpedo rudders retained their angle when the steering pulleys stopped. Rudder angle returned to zero when the helmsman returned the two steering pulleys to their centralised side-by-side location.

This type of steering differs from conventional steering for a vessel where the rudder angle only depends on the steering wheel angle of rotation instead of the steering wheel speed of rotation.

Shore stations

The torpedo was accepted into service in 1887. Shore stations were installed at eight sites – River Thames (Cliffe Fort), Sheerness (Garrison Point Fort), Portsmouth (Cliff End, Isle of Wight), Plymouth (Pier Cellars), Cork Harbour (Fort Camden), Malta (Tigne and Ricasoli) and Hong Kong (Lye Mun). The Lye Mun station was for the Lei Yei Mun channel to Victoria Harbour. All sites had a Directing Station, Slipway, Wire Room, General Store, Boiler Room, Engine Room, Torpedo Room and Coal Store. Some sites had an Accumulator Room, Engine and Generator Room, and Workshop. The station was under the command of a Station Torpedo Officer responsible to the Local Officer Commanding Submarine Mining. The number of men at a station varied. At Cliffe Fort in 1904 the detachment was one Officer, one Mechanist, one Engine Driver, and seven other ranks, sometimes referred to as Brennists. There appear to have been twelve torpedoes at a home shore station and twenty four at shore stations abroad. When a torpedo was launched it ran down the slipway on a four-wheel trolley and the propellers were running before the torpedo entered the water. The torpedo was never fired in anger but there was an annual competition for the Brennan Torpedo Challenge Cup, shore stations firing twelve torpedos. Cliffe Fort won the 1906 competition and the results give an indication of the effectiveness of torpedo guidance. There were six hits and five misses by less than 30 m for twelve firings against targets at 28 to 31 knots and ranges of 450 to 1100 m.

Shore stations were operated in conjunction with minefields controlled by an electric cable from another shore station. Both types of station were manned by the Submarine Mining Branch of the Royal Engineers.¹⁴ Defence Electric Lights were used to define the areas of responsibility for controlled minefields and torpedoes.

Security was a prime concern and ‘All officers, non-commissioned officers and men employed in torpedo installations shall make and sign a declaration of secrecy, before the Commanding Royal Engineer.’¹⁵ Civilian workmen were restricted to their actual working area and also signed the form. To assist in torpedo security the depth and steering mechanisms were factory sealed, and the seals were regularly checked and recorded in a register by the Station Torpedo Officer. The Colony of Victoria provided financial assistance for the early development of the torpedo and requested the supply of torpedoes. This request was denied by The Secretary of State for War ‘until experience has shown what precautions may be necessary for the protection of the secret’.¹⁶

The Rifled Muzzle Loader Gun was replaced by the far more effective Breech Loader 9.2 inch gun. The latter was adopted for coastal defence (including Australia circa 1890) and Brennan stations were closed by 1911. The remains of some stations, such as Cliffe Fort, are still visible. Brennan torpedo No. 18 is on display at the Royal Engineers Museum, Gillingham, and a replica torpedo is on display at the Hong Kong Museum of Coastal Defence, Lye Mun.

Final Tribute to the Inventor Extraordinaire and Wizard of Oz

Louis Brennan was buried on 26 January 1932 in an unmarked grave in plot number 2454 at St Mary’s Cemetery, Kensal Green, London, an inconspicuous final resting place for such an internationally renowned and talented inventor. To redeem this situation, on 11 March 2014 Mr Enda Kenny, the Taoiseach (Irish Prime Minister), unveiled a new headstone and plaque at a Service of Thanksgiving and Remembrance dedicated to the man credited with inventing the steerable torpedo and monorail system. A wreath was laid by the Australian representative CMDR Dylan Findlater, RAN.

Eade, Joel (1823-1911), Australian Dictionary of Biography, Volume 4, (MUP), 1972.
Smith, Alexander Kennedy (1824 – 18881), Australian Dictionary of Biography,

adb.anu.edu.aui/biography/smith-alexander-kennedy-4597. (10 February 2014)

Melbourne, The City Present & Past, Multimedia Content, Brennan Torpedo,

www.emelbourne.net.au/biogs/EM00231b.htm. (10 February 2014)

Melbourne, The City Present & Past.
Brennan Torpedo, en.wikipedia.org/wik/Brennan-torpedo (15 February 2014).
Louis Brennan’s Heavyweight Balancing Act – The Gyro-Monorail, theoldmotor.com/ ?p=109924. (15 February 2014)
Brennan helicopter –development history, photos, technical data

www.aviastar.org/helicopters_eng/brennan.php. (13 February 2014)

The Brennan torpedo, Submerged, www.submerged.co.uk>Special Reports>Bombs And Bullets. (15 February)
Glide bomb, en.wikipedia.org/wiki/ Glide_bomb. (22 January 2014)
Whitehead Mark 3 Torpedo, en.wikipedia.org/wiki/Whitehead_Mark_3_torpedo. (22 January 2014)
Russian/Soviet Mines, www.warships1.com/ WEapons?WAMRussian_Mines.htm. (18 February 2004).
Cowie J.S., Mines, Minelayers and Minelaying, Oxford University Press, London, 1949, p35.
Beanse reports that it has not been possible to examine the steering mechanism, and some components of the only extant torpedo are missing.
Controlled mines were detonated when a target was seen to be in a suitable location. See Cowie, p24. All controlled minefields became an Admiralty responsibility in 1905.
Memoranda for Station Torpedo Officer, Public Record Office (PRO) (UK) WO32/6065. (cited by Beanse).
The Brennan Torpedo 1881-1887, PRO WO32/6065. (cited by Beanse).

The Effectiveness of Torpedoes and Mines in World War II

March 24, 2014

By Mike Turner

Mike Turner graduated from Sydney University with a degree in Science and an Honours degree in Aeronautical Engineering. After qualifying as a Ships Diver in 1957 he joined the RAN Mine Countermeasures Development Unit (MCDU) at HMAS Rushcutter to develop a towed diver search system. Transferring to the RAN Experimental Laboratory (RANEL) he was involved in mine identification and the ‘half-necklace’ ship’s bottom search for Ships Divers. Working in just about all areas of mine countermeasures (MCM) included the observation and analysis of multi-national MCM exercises. The final project before retiring in 1990 was the development of MCM equipment, particularly ‘Dyad’ magnetic sweeps, to enable the RAN to use ‘Craft of Opportunity’ as minesweepers.

Submarine Torpedoes and Aerial Mines

Submarine torpedoes and aerial mines were the two major weapons used against warships and merchant ships in World War II, and were used to good effect by America, Britain and Germany. In contrast Japanese submarines sank very few Allied ships, and Japan lacked an aerial mine for mining in Allied held waters (offensive mining).

All losses stated in this article must be treated with due caution, and generally refer to ships over 500 tons.

Ships sunk by torpedoes

The torpedo is the ‘weapon of choice’ for submarines attacking ships. Japanese submarines sank 18 ships over 500 tons in Australian waters, and they were all sunk by torpedoes.¹ In a listing of 1,242 Merchant Navy ships sunk by U-boats 1,141 (92%) were sunk by torpedoes and only 101 (8%) were sunk by gunfire or the combination of torpedoes and gunfire.²

The major submarine offensive by the German U-boats in the ‘Battle of the Atlantic’ sank 2,788 ships and, assuming that 92% were sunk by torpedoes, 2,561 ships were sunk by German torpedoes.³

Ships sunk by mines

The largest offensive mining operation in World War II was the laying of about 50,000 British ground mines in NW Europe by British aircraft for the loss of approximately 500 aircraft.⁴ British mines sank 1,043 Axis ships compared to about 432 Axis ships sunk by British submarines.⁵

From a British viewpoint mines accounted for more shipping losses than submarines. This is probably the genesis of the common myth that ‘In World War II mines sank more ships than any other weapon.’ More ships were sunk by German torpedoes than were sunk by the mines laid by all countries. Whilst the table on the following page does not show losses due to torpedoes alone it gives a reasonable indication of the relative losses due to torpedoes and mines.

Enemy ships sunk in World War II

Theatre	Country	Enemy ships sunk by the country’s
Theatre	Country	Mines	Submarines
Europe	Britain	1,043	432
	Germany and Allies	802⁶	2,788
	Both sides	1,845	3,220
Pacific	America and Allies⁷	267	1,369
	Japan	16⁸	44⁹
	Both sides	283	1,413
Both theatres	All	2,128	4,633

Minefield effectiveness

The number of mines laid per ship sunk is often used as a criterion for minefield effectiveness. It is easy to derive this simplistic statistic, but it normally lacks relevance. A minefield has the capability to sink ships or submarines, and this capability makes its threat credible. However the real function of a minefield is not the sinking of ships. It is the control of the movement of enemy ships and submarines, and is difficult to quantify. The aim of tactical mining may be to control the movement of shipping such that it is more vulnerable to attack by other means, for example divert shipping into deeper water where it is more vulnerable to submarines. Control of an enemy’s shipping results from the enemy’s perception of potential damage rather than the number of mines and mine technology per se. It is human nature to overestimate the threat from unseen weapons such as mines. The mine has a psychological warhead, and ‘the real effect of a minefield derives from a more subtle influence- an exaggerated fear. Minefields work more on the mind than on ships.’¹⁰

No ships are sunk by mines when an ideal mining operation prevents any movement of shipping. A classic example of such an operation was a USN mining operation after 32 ships at Palau Atoll in the Caroline Islands were located on 30 March 1944. That night 78 Avenger torpedo-bombers from the carriers US Ships Lexington, Bunker Hill and Hornet ‘bottled up’ these targets by each laying an American Mk 10 moored mine or an American Mk 25 ground mine.¹¹ Although an attack next day seemed to be assured no ship attempted to flee to safety that night due to the psychological warhead of the mines. The carrier aircraft returned next day and 23 vessels over 500 tons were sunk by bombs and torpedoes, the average size being 4,425 tons.¹² The other nine vessels had also been reported as sunk, and presumably were all under 500 tons.¹³

A more recent example of an effective mining operation that did not sink any ships was at Haiphong during the Vietnam War. The initial minelay was by three A6-A and six A7-E aircraft from USS Coral Sea on 9 May 1972, and each aircraft laid four American Mk 52 ground mines with an arming delay.¹⁴ The thirty two ships at Haiphong were assured by American President Richard Nixon that these mines would not arm for three days, and five ships departed.¹⁵ The other 27 ships chose to stay in port, and traffic flow was reduced from 40 ships a month to zero. Mining was sustained and had significant psychological, political and military impact at the time. No ship entered the shipping channel until TF 78 swept a channel in 1973 (Operation END SWEEP). This American clearance operation was a vital lever in obtaining the release of American POWs.¹⁶

The effectiveness of a strategic minefield can be expressed as the reduction in traffic as a percentage of the traffic prior to mining. Operation STARVATION was the attrition strategic mining of Japanese and Korean home waters by American aircraft during World War II. It was in five phases. In Phase One 2,030 ground mines were laid from 27 March 1945 to 3 May 1945, and 12,321 ground mines had been laid by US Army Air Force (USAAF) and USN aircraft when Phase Five concluded on 5 August 1945. The effectiveness of this operation is demonstrated in the figure, where the width of a ‘route’ in the figure is proportional to the average tons of shipping per day. Mining in the vital Shimonoseki Strait was 92 percent effective, traffic being reduced from about 800,000 tons per month to about 60,000 tons per month. Mining was completely effective along the east coast of Japan, and all the ports were closed.¹⁷

It is rarely possible to quantify the effectiveness of tactical mining conducted to support other operations. This would require a comparison of enemy losses for the actual scenario (which includes tactical mining) with enemy losses for the hypothetical scenario in which there is no tactical mining.

Summary

In World War II torpedoes sank more ships than mines. However mine effectiveness is not measured by ships sunk or damaged. It is measured by the psychological impact of a weapon that waits and by the control of the movement of shipping such a threat imposes The minefield is a unique weapon in that it can pose a threat without any forces being present and can be used to enforce a blockade without risking forces. A minefield can deny free movement to enemy surface and submarine forces as well as neutral shipping.

The threat of mining can cause an enemy to divert very large resources from the ‘sharp end’ to defensive mine counter-measures (MCM). In World War II the total MCM effort for America, Britain, Germany and Japan was 3,230 ships and 146,000 men. This included the German effort of ‘46,000 men and officers, 1,276 sweepers, 170 boats and 400 planes’.¹⁸ By 1945 German MCM effort comprised 40 percent of all naval activity.¹⁹

1 Ships attacked off the Australian coastline by Japanese submarines. www.ozatwar.com /japsubs/shipssunk.htm (26 September 2013). (Vessels over 500 tons)

2 Merchant Navy Losses, www.battleships-cruisers.co.uk/merchant_navy_losses.htm (12 August 2013).

3 Ships hit by U-boats in WWII, www.uboat.net. (14 August 2013)

4 J C Cowie, Mines, minelayers and minelaying, Oxford University Press, London, 1949, p164.

5 Includes many Italian ships. See Campaign summaries of World War 2. British submarines at war. www.naval_history.net/WW2 CampaignBritishSubs2.htm (14 August 2013).

6 J C Cowie, Mines, minelayers and minelaying, London, Oxford University Press, 1949, p166.

7 The Joint Army-Navy Assessment Committee NAVEXOS P 468, Japanese naval and shipping Losses during World War II by all causes, 1947, www.history.navy.mil/library/online/japaneseshiploss.htm‎ (11 August 2013). (Vessels over 500 tons)

8 See U.S. Merchant Ships Sunk or Damaged in World War II, www.usmm.org/mineships.html (14 August 2013) and Casualties, Navy and Coast Guard Ships, WW II, www.history.navy.mil/faqs/faqs82-1.htm (30 April 2005).

9 Ships sunk by Japanese submarines, http://en.wikipedia.org/wiki/Category:Ships_sunk_by_Japanese_submarines (15 August 2013). This source lists 33 ships, and excludes 11 of the 18 ships sunk in Australian waters. (Vessels over 500 tons)

10 JC Bartholomew and WL Greer, Psychological aspects of mine warfare, Professional Paper 365, Center for Naval Analyses, Virginia, 1982, p5.

11 BR 1736 (50) (5), The Blockade of Japan, Admiralty, 1957 as CB 3303 (5), p35.

12 The Joint Army-Navy Assessment Committee NAVEXOS P 468, Japanese naval and shipping Losses during World War II by all causes.

13 R.C. Duncan, America’s Use of Sea Mines, US Government Printing Office, Washington, 1962, p39.

14 USS Coral Sea CVA 43. www.navysite.de/cvn/cv43.htm (2 October 2010)

15 J.S. Chilstrom, thesis, Mines Away! The significance of US Army Air Forces Minelaying in World War II, Chapter 6, Maxwell Air Force Base, Alabama, 1992. www.maxwell.af.Mil/au/aul/aupress/SAAS_Theses/SAASS_Out/Chilstrom/ Chilstrom_about_out.htm (13 December 2004).

16 Operation End Sweep, www.geocities.com/Pentagon/Bunker/2170/operationendsweep.html, (28 November 2004).

17 BR 1736 (50) (5), The Blockade of Japan, pp126, 155.

18 G.K. Hartman and S C Truver, Weapons That Wait, Annapolis, Naval Institute Press, 1991, p236.

19 J.S. Chilstrom, thesis, Mines Away! The significance of US Army Air Forces Minelaying in World War II, Chapter 2.

Letter: Sea mine

December 13, 2013

The article by Sub-Lieutenant N.J. Laing, RAN in the June 2013 Review quotes the myth that the sea mine ‘accounted for more shipping losses than any other weapon’ during World War II. This myth has been handed down from generation to generation in the mine warfare community, and often appears at the start of articles or presentations. Whilst data on shipping losses is incomplete it is adequate for a broad comparison of losses due to mines and submarine torpedoes.

The largest offensive mining operation in World War II was the laying of over 50,000 mines in NW Europe by British aircraft for the loss of approximately 500 aircraft. British mines sank 1,043 Axis ships compared to about 432 Axis ships sunk by British submarines. For Britain in the European context mines accounted for more shipping losses than submarines, but this was not the case for other countries.

In Europe the Axis powers sank 802 Allied ships by mines and 2,788 Allied ships by submarines. In the Pacific the Allies sank 287 Japanese ships by mines and 1,369 Japanese ships by submarine.

The overall total for the European and Pacific theatres were 2,132 ships sunk by mines and 4,589 ships sunk by submarines. Most of the ships sunk by submarines were by torpedo alone, and torpedoes sank far more ships than mines.

Yours sincerely

Mike Turner

By Editor: A response has been made thanking Mr Turner for bringing this to our attention. The referenced NEOC essay addresses the proud history of mine warfare in the RAN and provides a well-balanced and factual account of this aspect of naval warfare. However the quotation used at the run-in to this essay is misleading when stating that the sea mine accounted for more shipping losses than any other weapon. As outlined above more overall shipping losses are attributed to the torpedo rather than mines during WW II.

Torpedo

August 2017

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