Temistocle

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Hi, I searched the entire forum, but I did not find a thread about the Cultivator Number 6, a projected trenching machine; maybe it is well known to some of the readers, but I think it need a thread due to its particularity. Here the Cultivator as described by Winston Churchill in his book "Gathering the storm", Volume 1 of his World War II history:

Appendix J, Book II
CULTIVATOR NUMBER 6
During these months of suspense and paralysis [end 1939, beginning 1940, ndr] I gave much thought and compelled much effort to the development of an idea which I thought might be helpful to the great battle when it began. For secrecy’s sake this was called “White Rabbit Number 6,” later changed to “Cultivator Number 6.” It was a method of imparting to our armies a means of advance up to and through the hostile lines without undue or prohibitive casualties. I believed that a machine could be made which would cut a groove in the earth sufficiently deep and broad through which assaulting infantry and presently assaulting tanks could advance in comparative safety across No-Man’s-Land and wire entanglements, and come to grips with the enemy in his defences on equal terms and in superior strength. It was necessary that the machine cutting this trench should advance at sufficient speed to cross the distance between the two front lines during the hours of darkness. I hoped for a speed of three or four m.p.h.; but even half-a-mile would be enough. If this method could be applied upon a front of perhaps twenty or twenty-five miles, for which two or three hundred trench-cutters might suffice, dawn would find an overwhelming force of determined infantry established on and in the German defences, with hundreds of lines-of communication trenches stretching back behind them, along which reinforcements and supplies could flow. Thus we should establish ourselves in the enemy’s front line by surprise and with little loss. This process could be repeated indefinitely.
When I had had the first tank made twenty-five years before, I turned to Tennyson d’Eyncourt, Director of Naval Construction, to solve the problem. Accordingly I broached the subject in November to Sir Stanley Goodall, who now held this most important office, and one of his ablest assistants, Mr. Hopkins, was put in charge with a grant of one hundred thousand pounds for experiments. The design and manufacture of a working model was completed in six weeks by Messrs. Ruston-Bucyrus of Lincoln. This suggestive little machine, about three feet long, performed excellently in the Admiralty basement on a floor of sand.
Having obtained the active support of the Chief of the Imperial General Staff, General Ironside, and other British military experts, I invited the Prime Minister and several of his colleagues to a demonstration. Later I took it over to France and exhibited it both to General Gamelin and later on to General Georges, who expressed approving interest.
On December 6, I was assured that immediate orders and absolute priority would produce two hundred of these machines by March, 1941. At the same time it was suggested that a bigger machine might dig a trench wide enough for tanks. On February 7, 1940, Cabinet and Treasury approval were given for the construction of two hundred narrow “infantry” and forty wide “officer” machines. The design was so novel that trial units of the main components had first to be built. In April, a hitch occurred. We had hitherto relied on a single Merlin-Marine type of engine, but now the Air Ministry wanted all these, and another heavier and larger engine had to be accepted instead. The machine in its final form weighed over a hundred tons, was seventy-seven feet long, and eight feet high. This mammoth mole could cut in loam a trench five feet deep and seven-and-a-half feet wide at half-a-mile an hour, involving the movement of eight thousand tons of soil. In March, 1940, the whole process of manufacture was transferred to a special department of the Ministry of Supply. The utmost secrecy was maintained by the three hundred and fifty firms involved in making the separate parts, or in assembling them at elected centres.
Geological analysis was made of the soil of Northern France and Belgium, and several suitable areas were found where the machine could be used as part of a great offensive battle plan. But all this labour, requiring at every stage so many people to be convinced or persuaded, led to nothing. A very different form of warfare was soon to descend upon us like an avalanche, sweeping all before it. As will presently be seen, I lost no time in casting aside these elaborate plans and releasing the resources they involved. A few specimens alone were finished and preserved for some special tactical problem or for cutting emergency anti-tank obstacles. By May, 1943, we had only the pilot model, four narrow and five wide machines, made or making. After seeing the full-sized pilot model perform with astonishing efficiency, I minuted “cancel and wind up the four of the five ‘officer’ type, but keep the four ‘infantry’-type in good order. Their turn may come.” These survivors were kept in store until the summer of 1945, when the Siegfried Line being pierced by other methods, all except one was dismantled.
Such was the tale of “Cultivator Number 6.” I am responsible but impenitent.


There is a breif account about the travel for the demonstration in France in the book "Winston Churchill's Toy Shop" by Stuart Macrae.
More info about the Cultivator in the following links, with pictures and drawings:


Cultivator (Wikipedia)

ThinkDefense
 
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riggerrob

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Poor Bloody Infantry always welcome any machine that will speed trench digging.

The engineer version of Leopard 1 had an auger about a metre in diameter to quickly dig fox holes. officially, the auger was for planting telephone poles, but could be applied to a dozen other excavating tasks.

During the 1950s, the US Army even experimented with explosives to help dig trenches. The explosives were shaped charges like mortar bombs. They were positioned, tirggers pulled and infantry stood back to enjoy the explosion. Then PBI grabbed shovels to remove the loosened dirt. PBI especially appreciated these explosive diggers in rocky or rooted ground.
Sadly, the explosive device never progressed to large-scale service.
 
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Pioneer

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As a former Assault Pioneer, who's accustomed to digging trenches and fighting pits, I find it odd that the likes and calibre of the British and American armies can't get their heads, let alone field a simple and effective trenching vehicle.....After all the German's appeared to have formulated such a piece of machinery in the form of the A7V Schützengrabenbagger LMG Trench Digger in, 1917-1918, and of course, the Soviet Army fielded the excellent Soviet BTM-3 and PZM-2 trenching machines.

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A Tentative Fleet Plan

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As a former Assault Pioneer, who's accustomed to digging trenches and fighting pits, I find it odd that the likes and calibre of the British and American armies can't get their heads, let alone field a simple and effective trenching vehicle.....After all the German's appeared to have formulated such a piece of machinery in the form of the A7V Schützengrabenbagger LMG Trench Digger in, 1917-1918, and of course, the Soviet Army fielded the excellent Soviet BTM-3 and PZM-2 trenching machines.

Regards
Pioneer
Cultivator No.6 was intended to be used in a completely different manner to the other trench diggers you described, and was intended to lead an attack on the Siegfried line by digging trenches towards the defences, in which infantry and and armour would follow.
 

PMN1

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As a former Assault Pioneer, who's accustomed to digging trenches and fighting pits, I find it odd that the likes and calibre of the British and American armies can't get their heads, let alone field a simple and effective trenching vehicle.....After all the German's appeared to have formulated such a piece of machinery in the form of the A7V Schützengrabenbagger LMG Trench Digger in, 1917-1918, and of course, the Soviet Army fielded the excellent Soviet BTM-3 and PZM-2 trenching machines.

Regards
Pioneer
Cultivator No.6 was intended to be used in a completely different manner to the other trench diggers you described, and was intended to lead an attack on the Siegfried line by digging trenches towards the defences, in which infantry and and armour would follow.

I've never really understood the 'aim here' idea behind the cultivator......I can just picture a Looney Tunes cartoon with a trail snaking accross the terrain.
 

timmymagic

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I've never really understood the 'aim here' idea behind the cultivator......I can just picture a Looney Tunes cartoon with a trail snaking accross the terrain.

One of the best write ups on the web is, of course, on Think Defence's site. He's just updated it as well (I suspect with the pictures of the replica machine at Clumber Park, that I suspect I may have tipped him off to..). The replica is still there at Clumber (as of 2 weeks ago) and is rather large. It won't be there for ever as its made of wood though..so if you get the opportunity to view it do so soon, very nice place as well to spend a day wandering.

 

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The last source seems to erroneously (though understandably given some confusion in recent times) believe that none of the 'Officer' (also known as 'General') machines were completed.
 
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Grey Havoc

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An excerpt from the linked article:
After discussing the idea with the Director of Naval Construction (DNC), Sir Stanley Goodall, it was then passed to a former ship designer named JH Hopkins. The concept developed slightly and estimates of a top speed close to 1mph could be achieved, with the spoils forming a parapet to increase protection. The project was moved to a new department in the Ministry of Supply called Naval Land Equipment, or NLE, or Nellie in short. As the project progressed the design evolved to include a combination of a plough that would remove the top half of soil on top of a drum cutter and conveyor that would deal with the bottom half.

An examination of commercially available earthmoving equipment concluded that the Lincoln manufacturer Ruston-Bucyrus (who were in turn connected with the US manufacturer Bucyrus Erie) would be an invaluable source of expertise. Together with the Bassett-Lowke, a model was constructed for evaluation by the end of 1939.

Demonstration of the model was carried out in a sandpit in the basement of the Admiralty and in France, to a collection of British and French officers including General Gort. It was reported that all were suitably impressed and following a further demonstration for the Prime Minister and Chancellor of the Exchequer, authorisation to build 240 machines. This initial batch was going to be split between forty large machines called ‘Generals’ or ‘Officers’ and two hundred smaller machines called ‘Privates’ or ‘Infantry’.

NLE was also referred to as N.L.E., or more formally, D.N.L.E. Over the years the department has been occasionally confused with the Admiralty's Department of the Director of Naval Equipment.

Incidentally, the Director of Naval Construction's department (formally the Department of the Director of Naval Construction) was also known by it's other official, though much less used in practice, name of Directorate of Naval Construction. More usually though 'Director of Naval Construction' used on its own would refer to the Director and/or his department.
 
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