Talk:Sherman Firefly

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well, ill try and find better sources. but i read there were 2,200 mark 4 shermans(by british designations) and a similar number of mark2's. there were also some 1's. rich tea man.

information and image contradiction[edit]

Quote from the M4 Sherman page, in relation with the Sherman Firefly:

' The Americans were offered the 17 pounder, but the US Ordnance Department resisted having a British gun to replace the American cannon. '

And to add to this point, the first two lines of the Sherman firefly page:

' The Sherman Firefly (M4A4 VC Firefly) was a British variation of the M4 Sherman tank, fitted with the more powerful 17 pounder main gun. '

This is what I understand out of this:


The Sherman Firefly, was a Sherman variation, used by, and only by the British. The US Ordnance Department refused having their Shermans fitted with the British gun (17 pounder). As to follow up with this idea, I would say that the Americans would probably refuse to use the Firefly altogether, a British tank.


So what is wrong with this picture? The image used has its own information sheet (on the ground), and clearly shows an American flag, meaning obviously that this tank, as I or anyone would believe that it is a Sherman Firefly, as it is in the article of the tank in question, was in use by the Americans during the Second World War.

Could this be clarified? I could be wrong

pat 20:05, 6 January 2006 (UTC)[reply]

In fact toward the end of the war the US Army recognized the failings in its tank and tank destroyer guns, and ended up placing an order for (IIRC) 160, later reduced to 80, 17 pdr M4s, these being M4A3s IIRC. The first modified M4s were delivered to US armoured units just after the German surrender and were issued to occupational Constabulary units. After they were withdrawn they seem to disappear from the US Army's records.)
Only certain variants of the M4 were considered for conversion; for example diesel Shermans were discounted (mostly due to availability issues), and of the petrol Shermans only those with the wider M34A1 mantlet were used (the mantlet wasn't designed specifically for the conversion, as stated in the article). Another consideration was the specific manufacturer of the turret traverse mechanism, which depended on which plant produced them irrespective of marque, the Oilgear hydraulic system being the preferred type. Finally, although the designers managed to get the gun perfectly balanced it couldn't be fired on the move so the stabilisation system normally fitted to the 'standard' Sherman was removed.
Hence only certain Sherman I and Sherman V (US designations M4/M4 hybrid / M4A4) conversions existed. Sources:

[1](David Fletcher) and [2] (Steven Zaloga).

For easier identification in TOEs, if the Sherman marque had no letter suffix it was armed with the 75mm gun, if it had an 'A' suffix it had the 76mm gun, 'B' was assigned to the 105mm howitzer, 'C' to the 17 pdr. Hence the Sherman IIA, which was the M4A1 (76) serving almost exclusively with the British 1st and 8th Armies in the MTO, Sherman VC being the M4A4 Firefly conversion; etc. I don't recall any 105mm gunned Shermans serving with British or Commonwealth forces, but I may be wrong. Andy L 143.167.143.33 (talk) 18:43, 8 January 2016 (UTC)[reply]

Pat,

The picture is very odd - the tank is Belgian (see the small Belgian flag on the lower hull, next to the numbers "50055"). Now whether this tank is a former British Firefly or a former American M4A1(76) (armed with an American-made 76 mm gun M1) is anyone's guess - the Belgians had both types after the war. See this link: Sherman Register - Belgium

GMan552 05:51, 30 April 2007 (UTC)[reply]

The vehicle shown is a Sherman Firefly, the 17-pdr's rounded muzzle brake is quite distinctive (see here: Image:QF-17-pounder-batey-haosef-1.jpg) as is the gun's mantlet and the additional armour plate welded in front of the driver's and bow machine gunner's compartments. The tank is possibly a Firefly used by Belgium post-WW II or it may be a Belgian-crewed British WW II vehicle. The tank carries the British 'Bridge Classification' symbol (the '30' on a yellow circle - 30 tons weight) but that may have been carried by Belgian Army ones as well. Ian Dunster 14:06, 29 May 2007 (UTC)[reply]
It is one of the about two hundred Fireflies acquired by Belgium after the war, mostly from scrap dealers. The American flag is easily explained: the vehicle as such was produced in the USA, no? :o)--MWAK (talk) 11:51, 5 August 2008 (UTC)[reply]
Striclt speaking the Belgium vehicles weren't purchased from scrap dealers as they would have been demilitarized. They were in pretty much perfect working order but had been assigned to be scrapped by the War Office. AFAIK they were still on charge with the British Army, although some may have been ex-Polish. Loates Jr (talk) 03:27, 10 January 2016 (UTC)Andy L[reply]

It was a Sherman Firefly gunner who knocked out one of germanys leading tank aces during d day. there was an article in the mail several weeks ago about this and how several units who werent even in the area claimed the kill. the article goes on to explain what happened and how the Firefly got the jump on the german tank ace.Corustar 01:07, 11 July 2006 (UTC)[reply]

References

  1. ^ Sherman Firefly
  2. ^ M4 (76mm) Sherman

Gonna do some rewriting[edit]

The Book "British Armor in the Normandy Campaign 1944" has some good information that is lacking in this article. I will be reworking some of the information to expand the section and improve it.

-- Wokelly (talk) 20:59, 16 November 2007 (UTC)[reply]

Okay finally got around to rewriting the page. Added a bunch of new stuff, some new sections etc. Still need to do some stuff to it, find page numbers for sources for example. Given its length it would be nice to have a few more pictures. Personally I dont understand any of that copy right crap so I cant upload crap. If possible I would like pictures of a Firefly IC and IC hybrid. If anyone can help and upload those pictures it would be much appreciated. If you are having trouble distinguishing between the types its pretty easy one you realize the difference.

The Sherman Firefly picture we currently have is a VC, notice the curved lower hull that is bolted together.

A Sherman IC looks like this: http://www.etamiya.com/shop/images/tamiya_scalemodel/32532.jpg. Notice the lower hull is welded and not curved but more angular.

A Sherman IC hybrid looks like this: http://ww2photo.mimerswell.com/tanks/usa/med/m4/03797.jpg. Notice the curved upper hull.

So if someone could get pictures of both of those types that doesnt screw with the copyright stuff it would be much appreciated. Besides that we could just use a few pics overall to spice the the page. I just threw in some random pictures from the wiki commons for now.

Wokelly (talk) 05:44, 25 May 2008 (UTC)[reply]

I am not sure the above statements are correct re Sherman appearance. AIUI early M4s had a 3-piece transmission cover and later ones had a one-piece, of which there were two styles, one notably sharper-edged than the other. Fireflies were mainly conversions of the M4A4 but as the supply of these was finite Mark I and Mark I hybrids were also converted to make Mark Ic Fireflies. The interchangeability of Sherman parts was such that it seems quite hard to to be sure of what mark any vehicle is just based on the transmission cover. 89.207.1.20 (talk) 10:08, 29 January 2018 (UTC)[reply]

British AFV Gun limitations[edit]

The sole reason for the inadequate gun armament of British tanks during WW II was due to the parsimony engendered in the 1930's which would not allow the purchase of updated machine tools for/by the tank manufacturers. The limiting factor was the diameter of the turret ring, the size of which is decided by the capabilities of the cutting lathe. At the time, the UK had no lathes capable of cutting the turret ring larger than would accommodate a 6-pdr/75mm. Better guns were being developed,e.g., the 17 pdr, but the tanks were incapable of accepting them. This problem was subsequently solved by purchasing larger lathes from the US, and IIRC, the Centurion and Black Prince were the first UK tanks able to use the enlarged turret rings of the new machine tools. The Sherman had a larger turret ring and that's why the Firefly was able to mount the 17-Pdr. The Comet had the earlier size of ring, which was why the shorter-breech 77mm HV had to be developed. —Preceding unsigned comment added by 213.40.251.199 (talk) 22:56, 20 August 2009 (UTC)[reply]

I was under the impression that much of the inadequacy of British AFVs was down to the fact the War Ministry insisted on the vehicles being rail transportable. This is even more of a problem in the UK because it had (and has) one of the smallest loading gauges in Europe. This obviously limited their physical size and, by inference, the size of their turret ring, amongst other things. --JustinSmith (talk) 13:31, 9 January 2016 (UTC)[reply]

I have done some more checking up on this theory about British tanks needing to fit within the (relatively small) British loading gauge. According to "British & American Tanks of WWII" (Chamberlain & Ellis) the Centurion was the first British tank which the War Dept allowed to be over the loading gauge. As most people reading this would know the Centurion was a very good tank indeed, in fact, over all, most experts would rate it above a Panther or Tiger.--JustinSmith (talk) 13:41, 23 February 2016 (UTC)[reply]

These numbers seem to be uncontested on the internet. Sherman tank turret ring 69 in (1.8 m), Cromwell 60 in (1.5 m) with Comet at 64 inches and Challenger at 70 inches. Not that much in it. GraemeLeggett (talk) 16:15, 23 February 2016 (UTC)[reply]
I was always under the impression that what hobbled the development of a truly balanced gun-armour package in our tanks was that choice of armament was completely separated in the design phase throughout most of the war. Irondome (talk) 16:25, 23 February 2016 (UTC)[reply]

There is some truth in that, but if the tank cannot be over a certain size (so as to fit within the relatively small British railways loading gauge) that is obviously going to limit the size of gun which can be fitted in it. Certainly in a tank which also has decent armour protection.--JustinSmith (talk) 12:53, 24 February 2016 (UTC)[reply]

The cause was a combination of factors not the least being the lack of availability of engines of greater power than around 300-350 hp. This limited the size and weight of any vehicle, due to to the requirement to have an adequate BHP/ton ratio, quite apart from the railway loading gauge.
This limitation was lifted with the availability of the Rolls-Royce/Rover Meteor or around double that power. It was also helped by the introduction of specialised tank transporters which did away with the necessity to transport vehicles almost entirely by rail. — Preceding unsigned comment added by 86.8.126.91 (talk) 08:51, 17 October 2022 (UTC)[reply]

Perpetuating a myth[edit]

Currently:

...the importance of Caen to the Germans and Montgomery's operations which pinned German armoured forces in front of the British positions so the American units could break out to the west meant that British and Commonwealth units had to face over 70% of all German armour deployed during the Battle of Normandy, as well as almost all the elite, well-equipped SS units which contained the fearsome Tigers and Panthers. Thus, despite the relatively low number of Panthers and Tigers deployed, they would almost all be facing British and Commonwealth troops. As a result, the Sherman Firefly was perhaps the most valued tank by British and Commonwealth commanders, as it was the only tank in the British Army able to effectively defeat the Panthers and Tigers at the standard combat ranges in Normandy.

This passage starts with Montgomery's self-serving claims after the fact, (unfortunately taken at face value by some writers), and then apparently embellishes them even further. Montgomery was not trying to "pin German armoured forces so that the Americans could break out to the west," which was the story Monty later circulated but which is completely contradicted by his correspondence at the time. Operations Epsom, Charnwood, and Goodwood were full-on offensives which failed, not feints, diversions or spoiling attacks. Charnwood cost the assaulting infantry 25% of their strength. "The details of Operation Goodwood were settled two days later [July 12]: all three British armoured divisions would attack under the command of General O'Connor's VIII Corps, along a corridor blasted open by massed bomber forces. The aim was to strike fast through the German defences...and then race on across the great sweep of open country beyond The tanks would drive headlong for Falaise." As Monty wrote to Brooke at the time (contrary to his later version) : "So I have decided to have a real 'showdown' on the eastern flank, and to loose a corps of three armoured divisions into the open country about the Caen-Falaise road." Eisenhower wrote him saying "With our whole front acting aggressively against the enemy so that he is pinned to the ground, O'Connor's plunge into his vitals will be decisive."

The passage gets even more troubling in describing the opposition. In fact, while the 21st Army Group faced three Panzer divisions, two of them SS (the 1st and 12th), Bradley faced three as well, one SS (the 17th) and one the Army's elite Panzer-Lehr. Moreover, it's preposterous to claim that (A) the SS had all the Panthers and Tigers, or that (B) "almost all" of them were facing the British. Panzer-Lehr, in particular, was probably the best-equipped armored unit in the German OOB. --Solicitr (talk) 15:49, 2 January 2011 (UTC)[reply]

You need to read Battle for Caen. It is a fact that Panzer Lehr had only 2,200 men and 45 armored vehicles during Operation Cobra and 7 out of the 10 German Panzer Divisions were facing the Anglo-Canadian forces when the American armies launched Operation Cobra. ChristiaandeWet (talk) 01:07, 9 June 2012 (UTC)[reply]
There's a quote from Omar Bradley at the bottom of this section Talk:Operation_Goodwood#pov_citation_needed that shows just how different the forces facing the British and Canadians were, compared to those facing the US ones. Bradley had the decency to admit it, whereas many later US 'historians' tend to gloss-over the facts, the reasons for-which, you'd better ask them yourself. — Preceding unsigned comment added by 80.7.147.13 (talk) 15:34, 9 November 2012 (UTC)[reply]
" ... which is completely contradicted by his correspondence at the time." - Montgomery wasn't stupid enough to tell all-and-sundry the strategy he and Bradley had agreed upon. It was secret, as its success depended upon misleading the Germans as to where the breakout was to be, so drawing the majority of the armoured reserves onto the British and Canadians around Caen, and giving Bradly's Americans an easier time as any German armour the Americans knocked out would not get replaced from these reserves - the reserves were held east of Caen and so had to pass through Caen first before they could be sent on to the west to face Bradley.
Before D-Day the Germans were mislead as to where the actual landings would take place, Pas-de-Calais or Normandy, as a result Hitler ordered that the Wehrmacht's panzer reserves were to be held mid-way between the two locations. This is where the reserves where when Montgomery and Bradley were fighting after D-Day and so the reserves had to pass Montgomery's forces first before they could go on to face Bradley's. The fighting for Caen stopped the reserves intended to reinforce those fighting Bradley, instead they were being forced to be used in the defence of Caen itself - which the Germans were determined not to lose.
And being secret you don't go around telling the secret plan to people on your own side who might later be in a position to be captured and interrogated by the enemy. Nor do you included it in wireless signals in a cipher that for all you know the enemy might have broken. — Preceding unsigned comment added by 95.150.100.246 (talk) 16:22, 7 October 2016 (UTC)[reply]
The Panzer Lehr were almost destroyed in the fighting around Caen, as were the Hitlerjugend, such that Hitler personally ordered the latter division withdrawn from the battle. — Preceding unsigned comment added by 95.149.53.180 (talk) 17:45, 1 January 2020 (UTC)[reply]

sourcing - a possible issue[edit]

this section of Ironsides: Canadian Armoured Fighting Vehicle Museums and Monuments seems to match part of the section on urceservice. Having read the preface, the book uses wikipedia as a source. Thought it best to mention it, so we don't end up with circular and unreliable referencing. GraemeLeggett (talk) 18:42, 22 August 2012 (UTC)[reply]


A Tall Tale?

The article states that there were 2000 Firefly conversions produced by the British, and that they were an all important deterrent to the German Tigers. According to the History Channel, there were only 71 Firefly's produced, they were a re-action to the effect of the Tigers at and immediately after Normandy, thus not available at Normandy and overall did not have a big impact on the outcome of the conflict. This was partially due to limited British production capabilities and the willingness of Allied planners to take high losses in using the Sherman. So which is true? Is this author correct, or the History Channel? — Preceding unsigned comment added by 65.190.5.81 (talk) 22:13, 27 March 2013 (UTC)[reply]

The History Channel is wrong, very wrong, both on the timing of the Firefly, deployment, its effect and numbers produced. The article is correct and based on reliable and well-researched sources. The History Channel is not a reliable source. 46.194.165.219 (talk) 19:36, 21 June 2013 (UTC)[reply]

Agreed! Very wrong. I think the previous comment sounds like it was a joke too. Shire Lord 20:58, 25 June 2014 (UTC)

Alternative lead image[edit]

Can I suggest File:Sherman firefly bovington 2014.JPG? I feel it shows the tracks better.©Geni (talk) 02:20, 9 November 2014 (UTC)[reply]

Agreed, and done. (Hohum @) 12:08, 9 November 2014 (UTC)[reply]

The original lead image was much better - far more dramatic, and technically superior despite being seventy years old. You've replaced a pretty good historical shot with a blurry amateur snapshot taken in a tank museum. It's larger but looks awful up close. -Ashley Pomeroy (talk) 19:47, 12 May 2016 (UTC)[reply]

While I'm at it, what's your relationship? On images like this and this - which are inadequate for any purpose - you're a tag-team. Do you go around Wikipedia voting on each other's photographs? What's the point? User:Diliff absolutely wipes the floor with both of you and has successfully used Wikipedia as a marketplace for his work; you have the same equipment but you're never, ever going to match him. So what's the point? -Ashley Pomeroy (talk) 20:01, 12 May 2016 (UTC)[reply]

It certainly one of the classic British photographs of the war, and one of the best tank pics ever taken. I think it's a beautifully battle-weary Firefly of the 11th Armoured Div. They were going to be re-equipped with Comets but they got pulled into covering the northern flank with their knackered kit. Just adds to the pic imo. First saw it in the Battle of the Bulge edition of Purnell's History of the Second World War in 1975 when I was 14. It was 30p weekly, serious money. It is technically excellent and rather atmospheric. I am purely sticking to the topic here. Irondome (talk) 21:45, 12 May 2016 (UTC)[reply]
Not aware of any particular relationship. As for the lead image in this article as far as I can tell historically it was this added in 2005 then this. Then mine. Mine was simply the latest in a series of museum pics and since it shows the whole tank without cropping out anything or having anything in the viewer I'd stand by it being superior to its predecessors.
Moving onto the other photos. The objects in question still exist if anyone else can do better they are free to do so. Since you seem to care about what images look like when they are zoomed in I doubt you are going to be too happy about what we had of the warrior before I get involved. Doesn't help that the thing is a horrible photographic environment inside and out. That black paint is at least partial gloss and the most obvious way of photographing the thing gives you horrible glare what the sun is reflected via the water. As for the pluto image at the time it was uploaded it was our only image of the Pluto pipeline and is still the only one we have with the layers stripped back like that (and given your later reference to equipment give the Toshiba PDR-M25 cia 2001 a break).
Moving on to User:Diliff. Yes he's a better photographer than me. But unfortunately we can't clone him off a few hundred times. Our equipment isn't actually that similar. Depending on which of the sigma 150-600 he's got we've got at most two lenses in common (the other being the 24-105).
I'm not trying to market my work so that's not an issue. And the point is to have fun. I don't enjoy spending large amounts of time in posting stitching images together and combining differing exposures so even on a technical level I'm not going to come close to Diliff. I don't enjoy editing out backgrounds or perfecting lighting for studio shots so User:Evan-Amos is also out of reach. But hey I still produce photos that in certain areas are better than anything else we have. Perhaps one day we will work out how to clone off featured pictures takers but that seems to be a while off. ©Geni (talk) 01:16, 22 June 2016 (UTC)[reply]

only British tank capable of defeating[edit]

It's bad enough this isn't actually true, but it's laughable that Wikipedia didn't even bother to find one of the sources that repeats this false judgment, and instead cited a source that says nothing of the kind. Buckley has been subtly twisted so his point that only the 17 pdr APDS could defeat any German armor plating at combat ranges becomes a claim that only 17-pdr equipped tanks could defeat German tanks. Which is not what he says; he says the lesser ATGs had "limited success," had to fire from the flank, "had great difficulty," etc. And his overall conclusion is diametrically opposed to this old school / History Channel gun-centered view of the fighting in Normandy; he says tactical factors (basically, being on the offensive in extremely good defensive terrain) and doctrinal/operational failings were more important than technical factors. TiC (talk) 08:40, 21 March 2017 (UTC)[reply]

The Firefly was the only Allied tank on the Western Front (discounting specialised vehicles such as the Archer, Achilles, and Challenger) that could defeat any of the later German armoured vehicles at the sort of ranges required, which on open ground effectively means as soon as the enemy vehicle is sighted. All the other Allied vehicles had to get closer first and/or wait until they could fire at the side or rear of the vehicle before they could fire with any hope of destroying the German vehicle. During this period of waiting to fire the German tank could destroy any Allied vehicle at almost any range as soon as it was seen.
The article does, however, appear to overstate the anti-armour performance of the 17-pounder, citing a hokey source. The figures given in the official history, LF Ellis, Victory In The West Vol. I, HMSO 1962, ISBN 1-870423-07-0, table p.549, are these:- 17-pdr, Mark II, APCBC, penetration against homogeneous armour plate at 30 degrees: at 100 yards, 149mm; at 500 yards, 140mm; at 1,000 yards, 130mm; at 2,000 yards, 111mm. (Equivalents with DS 'Sabot' ammo 221mm, 208mm, 192mm, 161mm, but 17-pdr 'sabot' was not issued to the tanks, only to RA anti-tank units, and only from August 1944 in small quantities.)
The article is, however, quite correct to claim that the Firefly outgunned both the Tiger I ('Tiger Ausf E' to the Wehrmacht) and the Panther. The equivalent figures for the Tiger's 88m KwK 36 are: at 100 yards, 120mm; at 500 yards, 112mm; at 1,000 yards, 102mm; at 2,000 yards, 88mm. For the Panther's 75mm KwK 42: at 100 yards, 138mm; at 500 yards, 128mm; at 1,000 yards, 118mm; at 2,000 yards, 100mm. Only the 'long' 88mm KwK 43 of the King Tiger (Tiger Ausf B) and the Jagdpanther outgunned the Firefly (202mm, 187mm, 168mm, 137mm), and those vehicles were rare.
Ellis's notes, in the confidential Cabinet Edition, p.638, cite, for the Allied guns, 'RAC Centre, Bovington, file INV 3/2: infromation sheet, 9 March 1945 and folios 12a, 44 and 46 [Cab/Hist/V/I/I]; Reference 12 above [Half-yearly report on the progress of the Royal Armoured Corps, Jan/June 1944, Appx.F]; OB/43/CV/11; OB/43/80B; US Army Technical Manual 9/2300 Artillery.' And, for the German guns, 'Reference 21 above [Wa Pruf (BuM) I/W, folder of 5 Oct 1944[SCB/H15/135]; EDS/AL581, vol.III.]; Ordnance Board letter of 16 May 1960 and notes [Cab/Hist/V/I/I]; EDS/AL581, vol.II, Part I.' Khamba Tendal (talk) 20:14, 14 November 2019 (UTC)[reply]

Wittmann[edit]

I deleted a paragraph someone inserted, cited to a thoroughly hokey source (Bird), claiming that 'photographs' prove Wittmann's Tiger 007 was hit from the left side and therefore the Canadians did it. There is only one extant photograph of Tiger 007 after its destruction, it was taken from the rear and shows the back end of the vehicle with the blown-off turret lying in the field behind it, and it cannot possibly support any such hypothesis. It shows, perhaps, some untidiness on the left side, suggesting something blew out from the inside during the explosion that took off the six-tonne turret, but an inbound anti-tank round would not create that outward deformation of the metalwork. The Canadian unit's war diary was destroyed that day and there is no proof that they were even in position at the relevant time. Nor did any individual from that unit ever attest to taking the required shot or seeing the explosion (which Ekins did see, and only one Tiger exploded during that action, and it was Wittmann's). The destruction of Tiger 007 is credited to Joe Ekins of the Northants Yeomanry for sound, documented reasons. Undocumented retrospective claims, made long after the war, solely on account of Wittmann's posthumous celebrity in revisionist literature, with no reference to records kept on the day, are of no value. Khamba Tendal (talk) 19:43, 14 November 2019 (UTC)[reply]

Canadians were much closer and considering how stories started circulating very late, has Ekins, a tanker who barely shot a cannon by the time, fairly questionable chance of achieving three consecutive hits over 1200m. It all sounds overly self-promoting. Ddelete013 (talk) 22:37, 20 August 2021 (UTC)[reply]

Can we stop writting self-serving patriotic pieces?[edit]

There is no source on neither the tank being actually an advantage, nor that Germans cared about it.

The idea that the British were to pin down Germans in order for the US to be able to make a long detour around the bridgehead is also bollocks. Montgomery's plans started with the aim of a breakthrough and shifted towards limited objectives mid-way through the battle of Caen. The reason being that the British couldn't get through.

Such propaganda does a lot of harm to the credibility of Wikipedia. Ddelete013 (talk) 22:49, 20 August 2021 (UTC)[reply]

What specific changes are you suggesting for this article? GraemeLeggett (talk) 06:58, 21 August 2021 (UTC).[reply]
Do you have any sources to back up your claim Ddelete013 (talk)? Eastfarthingan (talk) 09:39, 21 August 2021 (UTC)[reply]
Yes, delete unsubstantiated parts. Find evidence first. Simple. Alternatively, it can be written that firefly's impact is unclear. Providing three random examples of it destroying German tanks proves nothing.
Sources to back up the lack of sources? How does that work? Ddelete013 (talk) 12:08, 22 August 2021 (UTC)[reply]
The plan for the British and Canadians to take on the bulk of the German armour and prevent it getting through to the American sector is outlined in both Bradley's and Montgomery's memoirs both of which were published as early as the 1950's.
Rommel prior to D-Day asked von Rundstedt for 9 Panzer divisions to defend Normandy and von Rundstedt gave him nine. Of these nine the British and Canadians fought initially eight, later falling to seven, leaving only one, and later two divisions, that eventually got through to Bradley's sector.
The Allied D-Day planners knew all about these 9 Panzer divisions, their names, their size, where they were stationed, right down to the units constituting them, and the names of the unit commanders. So Bradley and Montgomery knew the respective size and strength their forces would be facing months, or weeks, before the landings began. So neither Bradley nor Montgomery thought taking Caen would be anything other than a long, hard, fight.
This is neither obscure information nor is it hard to find.