Canadian pipe mine

The Canadian pipe mine, also known as the McNaughton tube, was a type of landmine deployed in Britain during the invasion crisis of 1940-1941. It comprised a horizontally bored pipe packed with explosives, and once in place this could be used to instantly ruin a road or runway thereby denying its use by an enemy.^[1][2][3]

Development

The Canadian 1st Division under the command of Lieutenant-General Andrew McNaughton arrived in England in December 1939. They were not initially sent to France with the British Expeditionary Force (BEF) and therefore were not caught up in the escape from Dunkirk, although they were very briefly deployed to Brest in north-western France. On their return the No 1 Tunnelling Company, Royal Canadian Engineers were employed in the preparation of field fortifications along the south coast of England. In this company were a number of men from British Columbia, the rugged and mountainous, westernmost province of Canada. Many of these men were highly skilled in the use of diamond-tipped bits for drilling into hard rock.^[3]

Somebody realised that the lightweight drilling rigs and pipe pushing machines could easily be adapted to the soft soils and sedimentary rocks of southern England and that the rigs themselves could easily be transported on the back of a truck or a road grader fitted with a steel platform. Soon, such rigs were being used to drill into the approaches to bridges or embankments, the pipe being left in the ground and filled with explosives ready for instantaneous demolition.^[3]

This idea was further developed to make an invisible anti-tank obstacle. The drills and pipe punching machines were used to bury a series of 3-inch (76 mm) diameter pipes, each at a shallow angle to a maximum depth of about 8 feet (2.4 m). Each pipe was about 55 feet (17 m) long and they were placed at intervals of 25 feet (7.6 m) in an overlapping pattern. The pipes were packed with explosives which when detonated would produce a very effective anti-tank obstacle about 28 feet (8.5 m) wide and 8 feet (2.4 m) deep with loose soil at the bottom.^[4][3]

Tactical use

A secret report emphasised the value of this obstacle:

The quality of surprise renders the obstacle of particular value in influencing the enemy's plan. Its use enables the enemy to be induced to stage his attack at a point where there is an apparent gap in the Anti-Tank defence while at the same time retaining the ability to stop him.

It is of particular value in the last minute construction of road blocks after the passage of our troops.

It must be emphasised that surprise is the chief characteristic of this obstacle not speed.^[4]

Conventional anti-tank obstacles were very obvious from the air. These pipe mines had the advantage of being virtually invisible from the air and so could be used when the enemy had been coaxed into a seemingly weak point in the defences. Furthermore, the mines could be set in place without interference to the normal use of the land and so they were deployed under roads and railways that might need to be blocked in an instant, and runways that may need to be denied to the enemy at short notice.^[4][5]

Originally known as the Canadian Pipe Mine, it was later named the McNaughton Tube Tank Obstacle in honour of the commander of the Canadian Corps, Lieutenant-General Andrew McNaughton.^[3]

On 9 August 1940, "McNaughton’s secret A/T obstacle" was demonstrated to General Brooke and met with enthusiastic approval.^[6] By October 1940, the skills of the Canadian engineers were in demand and consideration was being given to training further British units to install the devices.^[4] In due course, 179 Special Tunnelling Company of the Royal Engineers was formed.^[4][7] About 40,000 feet (12 km) of the obstacle were installed – requiring some 90 tonnes of explosives.

Problems

However, all was not well with the McNaughton tubes. Although it had been thought that the blasting gelatine explosives would remain potent for several years,^[4] by the spring of 1941 it was evident that the explosives in some of the tubes had been affected by water and its power had deteriorated significantly. A brass spearhead on a long rod was provided for withdrawing the explosives from the tubes, but in some cases the explosive had deteriorated into a porridge-like mush.^[4] Second Lieutenant Cameron, who as a civilian was a very experienced oil drilling engineer, suggested washing out the explosives with water delivered by a narrow diameter tube pushed down the main pipe. The mush, along with globules of nitro-glycerine was caught in hessian sacks and disposed of. The original pipes were then re-charged with more stable explosives.^[8]

Soon after the end of the war, almost all the Canadian pipe mine installations were removed. However, a small number were missed and rediscovered many years later when it was necessary to deal with them with great care.^[9] This happened in April 2006 when 20 unexploded pipe mines were discovered under a runway at a former Royal Navy air base, HMS Daedalus, Lee-on-Solent, Hampshire. 60 feet long, they were left over from an original 265, packed with a total of 2,400 lb of explosive. Their removal, thought to be the largest of its kind in peacetime Britain, led to the evacuation of some 900 homes staggered over a 5 week period.^[10] The mines were destroyed by controlled explosion.^[11][12]

See also

• British anti-invasion preparations of World War II
• British hardened field defences of World War II
• Camouflet

Notes

1. ^ "Canadian pipe mine". Thesaurus. English Heritage. http://thesaurus.english-heritage.org.uk/thesaurus_term.asp?thes_no=365&term_no=123417. Retrieved 30 September. 
2. ^ Foot 2006, p. 24.
3. ^ ^{a b c d e} Cameron 2006, p. 156.
4. ^ ^{a b c d e f g} McNaughton tubes; road cratering - WO 199/2661. The Catalogue, The National Archives
5. ^ "Glider Pilot Part 5". WW2 People's War (article A2465165). http://www.bbc.co.uk/ww2peopleswar/stories/65/a2465165.shtml. Retrieved 2 August 2010. 
6. ^ Alanbrooke. War Diaries 1939-1945. Entry: 9 August 1940.
7. ^ Cameron 2006, p. 157.
8. ^ Cameron 2006, p. 158.
9. ^ "Robodigger Vs Canadian Threat". Wired. http://www.wired.com/dangerroom/2007/08/frontline-bri-1/. Retrieved 2 August 2010. 
10. ^ "Bomb clearance moves into final stage". Hampshire Chronicle. 20 October 2006. http://www.hampshirechronicle.co.uk/archive/2006/10/20/++News+-++Latest+Headlines/980662.Bomb_clearance_moves_into_final_stage/. Retrieved 30 September 2010. 
11. ^ "Large bomb found at ex-Navy base". BBC News. 22 April 2006. http://news.bbc.co.uk/1/hi/england/hampshire/4934102.stm. Retrieved 2 August 2010. 
12. ^ "PIPE MINE CLEARANCE at Daedalus Airfield" (pdf). Hantsweb. http://www3.hants.gov.uk/300m_leaflet_final_version.pdf. Retrieved 30 August 2010. 

References

• Alanbrooke, Field Marshal Lord (2001). War Diaries 1939–1945. Phoenix Press. ISBN 1-84212-526-5. 
• Cameron, A Bryce (2006). Under Sand, Ice & Sea.. Trafford Publishing. ISBN 978-1552123195. 
• Foot, William (2006). Beaches, fields, streets, and hills ... the anti-invasion landscapes of England, 1940. Council for British Archaeology. ISBN 1-902771-53-2. 

External links

• "The National Archives". Repository of UK government records. http://www.nationalarchives.gov.uk. Retrieved 2 August 2010.