This is coolbert:
"For 'tis the sport to have the enginer
Hoist with his own petar; and 't shall go hard
But I will delve one yard below their mines
And blow them at the moon"
In the aftermath of the disastrous Dieppe landing
, it was realized by those planning the Normandy invasion  that SPECIAL
equipment would be required to breach German beach defenses and then subsequently when the allied forces moved inland.
[D-Day at Normandy was just the beginning
of a ninety-day campaign to defeat German forces in Normandy. A defeat that hopefully would result [it did too] it a precipitous Nazi retreat to the Rhine. D-Day was only the start
of the battle to liberate France!]
The use of tanks [armor] was seen as being essential for the landings at Normandy to be successful. Infantry wading ashore needed fire support to overcome German defenses.
Hobart’s’ Funnies were developed as an answer to the beach landing problem. Tanks that were modified with a variety of “apparatus”, each designed to solve a particular problem
associated with amphibious invasion and tank assault.
An amphibious version of the Sherman tank
[DD] was developed. A tank that had the capability to “wade” ashore and support that initial wave of troops landing at Normandy.
An additional tank, combat engineering modified, was developed that sported a “bobbin” mechanism on the front. Ungainly looking but having great utility for the amphibious assault.
"A reel of 10 foot wide canvas cloth reinforced with steel poles carried in front of the tank and unrolled onto the ground to form a 'path', so that following vehicles (and itself) would not sink
into the soft ground of the beaches"
Again, the landings at Normandy on June 6 would only be the beginning of the Normandy campaign. A campaign that would rely heavily on allied armor movements. Armor movements that needed to proceed without impediment.
It was also well understood by allied planners that a rapid tank advance by American and British tankers would be contested by German forces which were adept at employing anti-tank “stop lines”.
Anti-tank “stop lines” that were intended to slow down and delay further forward advance by tank units. Lines of defense that posed serious difficulties for allied commanders who desired a quick resolution to the Normandy campaign.
Anti-tank “stop lines” that would consist of the following, from front to rear, as viewed by the attacker:A minefield
consisting of anti-personnel and anti-tank mines both.An anti-tank ditch
.Above ground anti-tank obstacles
, such as dragon's teeth
, hedgehogs, concrete blocks, steel beam apparatus of varying designs, vertical steel piping [concrete filled] and wooden posts [telephone pole sized] anchored by concrete into the ground.Prepared defensive fortifications
, bunkers, pillboxes and anti-tank gun positions, pre-sighted and positioned to guard the “stop line”.
[an anti-tank “stop line”, like all other barriers, is no good unless guarded to some degree!! Modern anti-tank “stop lines” would include a tank-firing ramp. A wedge of earth from which a defending tank could fire by depressing it’s gun, presenting only the heaviest and thickest portion of frontal armor to the attacker. Israeli tanks defending the Golan Heights in 1973 utilized such ramps with great success!]
Beach defenses to stop tanks would have included a “tank wall”. An impressive concrete structure too difficult for tanks to scale. Sometimes being six feet in thickness. Allied tanks at Dieppe encountered such a wall? It seems that the wall at Dieppe was a sea wall, and not an anti-tank wall.
"Those tanks that did cross the sea wall were stopped by concrete roadblocks
.... the bogged-down vehicles became sitting ducks for the anti-tank guns."
[to defeat a "tank wall", the "Ark" could be employed.]
"Ark - Armoured Ramp Carrier was a Churchill tank without a turret that had extend able ramps at each end; other vehicles could drive up ramps and over the vehicle to scale obstacles."
These anti-tank “stop lines” sometimes measured tens of miles long [or even greater??] and were often arrayed in depth by the defender.SOVIET FORCES, WHILE ON THE OFFENSIVE, CONSTRUCTED SUCH STOP LINES TO A DEPTH OF FIFTY MILES. ALL THAT OCCURRING WHILE ON THE OFFENSIVE!
[this to defend against any possible German counter-attack!]
These “stop lines” posed a significant dilemma to advancing tank units. A problem that conventional combat engineering units of the time did not have a ready answer to.
[it would have been suggested at the time that conventional combat engineering units did possess a know-how and ability to breach these anti-tank “stop lines”. Existing units did have the wherewithal to do so, yes, but only with a large expenditure of time and manpower. Time is of the essence in an armored advance. Tank units pursuing an enemy could not wait for a laborious process to take place prior to resuming the advance!]
Hobart’s Funnies, once again, in a variety of manifestations, did offer a solution for combat engineering units attempting to breach the “stop lines”.
Ingenious and clever solutions WERE FOUND
that allowed combat engineers to defeat the various elements comprising the anti-tank “stop lines”.
To defeat the minefields, tank plows
["bullshorn"], mine rollers
, and tank flails
were all employed.
To defeat the anti-tank ditch, tank-borne bridging equipment
could be employed.
"Small Box Girder was an assault bridge that was carried in front of the tank and could be dropped to span a 30 foot gap in 30 seconds."
To defeat above ground anti-tank obstacles or pillboxes, a tank firing a petard spigot mortar demolition charge could be used.
"A petard mortar was the demolition weapon fitted to the Churchill AVRE tank. It was a mortar of a 290 mm bore
, known to its crews as the 'flying dustbin' due to the characteristics of its projectile: an unaerodynamic 20 kg charge, sufficient to demolish many bunkers and earthworks
A further weapon to defeat enemy bunkers and pillboxes was the flame-throwing tank
"Crocodile - A Churchill tank modified by the fitting of a flame-thrower in place of the hull machine gun. An armoured trailer, towed behind the tank, carried 400 Imperial gallons (1,800 litres) of fuel. The flamethrower had a range of over 120 yards (110 metres)."
There was available several versions of armored all-purpose bulldozers
that had a multiplicity
of applications, employed at the discretion of the combat engineers.
"Armoured Bulldozer - A conventional Caterpillar D8 bulldozer fitted with armour to protect the driver and the engine. Their job was to clear the invasion beaches of obstacles and to make roads accessible by clearing rubble and filling in bomb craters."
"Centaur Bulldozer, a Cromwell tank with the turret removed and fitted with a simple, winch operated, bulldozer blade. These were produced because of a need for a well-armoured, obstacle clearing vehicle that, unlike a conventional bulldozer, would also be fast enough to keep up with tank formations
There was even a "Canal Defence Light
" which could be used to blind and dazzle defenders at a crucial crossing point.
"It was based upon the use of a powerful carbon-arc searchlight to dazzle and confuse
"its true purpose was to blind the defenders
during a night attack and so help obscure attacking forces."
Combinations of these combat engineering vehicles [CEV] working in concert could be used to breach with speed and relative ease existing tank “stop lines”, facilitating further rapid advance by allied tank units.
Hobart’s Funnies are generally recognized as the forerunner of the modern CEV.
Necessity was the mother of invention. In large part also to the strong character of General Sir Percy Cleghorn Hobart.