It comprised a horizontally bored pipe packed with explosives, and once in place this could be used to instantly create an anti-tank obstacle or to ruin a road or runway thereby denying its use by an enemy.
[1][2][3] In November 1939 Lieutenant-General Andrew McNaughton travelled to Toronto for a meeting[4] with Lieutenant-Colonel Charles Hertzberg (Commanding Royal Engineers, CRE) and Lieutenant-Colonel Guy R. Turner, both of the 1st Canadian Infantry Division, Oliver Hall of the Mining Association of Ontario, and Colin Campbell, an experienced mining and construction engineer and Minister of Public Works under Ontario Premier Mitchell Hepburn.
The meeting participants discussed military possibilities raised by experimental diamond drilling, an initiative that had been broached by R.A. Bryce, president of the Ontario Mining Association, among others.
I did tell him that I wanted his Minister of Public Works in charge of a special section of tunnellers and so we finally compromised; I swapped the Premier of Ontario as an A.D.C.
[14] At a meeting with senior British engineers at Aldershot, McNaughton suggested that the pipes might be used to construct surprise obstacles in front of a German advance.
[15] According to McNaughton's biographer, John Swettenham, he got the idea of using hydraulic jacks from the bootleggers of Windsor, Ontario who, during the prohibition, pushed pipes from a brewery to other premises where drink could be safely loaded.
McNaughton noticed that ditches were being dug across unused airstrips to deny their use by the enemy, even though the bombing of active airfields might make them urgently needed in the near future.
[3] On 9 August 1940, "McNaughton's secret A/T obstacle" was demonstrated to General Alan Brooke, Commander-in-Chief, Home Forces, and, as such, responsible for defence of the UK.
[20] 179 Special Tunnelling Company of the Royal Engineers was formed,[20][23] and about 40,000 feet (12 km) of the obstacle were installed – requiring some 90 tonnes of explosives.
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.
[20] Second Lieutenant Cameron, who as a civilian was an experienced oil drilling engineer, suggested washing out the explosives with water delivered by a narrow diameter tube pushed down the main pipe.
[26] In April 2006, 20 unexploded pipe mines were discovered under a runway at a former Royal Navy air base, HMS Daedalus, Lee-on-Solent, Hampshire.