3in and 3.7in "CS tank" howitzers

Discussion in 'Weapons, Technology & Equipment' started by phylo_roadking, Feb 14, 2014.

  1. TTH

    TTH Senior Member

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  2. Sheldrake

    Sheldrake Gunner Tours


    There may be some fire under the smoke, and note merely a short round from a 3" howitzer...

    The true extent of the inter service rivalry and back biting between the corps over the use and ownership of weapons is not always well documented or written up.

    I am doing some work on the planning for D Day and some of the original diaries make for interesting reading. E.g. there was no love lost between RA 2 Army and the RAF; There was a lot of fun and games between the RA and RM over the RMASG' s Centaurs and one of the RN boffins is described as a "blighter."

    I think you are right that the ownership of Self Propelled HE firing artillery was in one of the border areas between the RA and RAC. I have heard somewhere that the reason why the SP version of the 3" 20 CWT AA gun did not enter service is because the RAC and RA squabbled over who owned it. One influence on the apparently retrograde replacement of the M10 Achilles in Atk Regiments in 1944-5 by the Archer was because the unit requirements from Normandy were much much too close to a Firefly. (M10 is great, but could the replacement have a better armoured closed turret and a coaxial MG)

    I can't find anything in the Gunner stuff from the inter war years. There were problems with the Birch Gun and after the mobile Brigade they were scrapped and the Gunners lost interest in SP Guns. The field ought to have been clear for the RAC to develop tanks which fired HE.

    It isn't just the British who have these problems. Guderian's "Panzer Leader" gives some glimpses of the rivalry between the Panzerwaffe and the Sturm Artillerie.

    This is a bigger topic than a foot note on an esoteric thread.abotu 3" and 3.7" CS howitzers

  3. mapshooter

    mapshooter Senior Member

    IIRC artillery telescopes were always for the top charge, direct fire dial sight could of course be any charge you wanted but of course usually involved adjustment in the normal manner. I've been trying to remember what the default charge was for 105mm Splintex, everyone's favourite for direct fire, it had a MT fze.

    WP and HC smoke are not the same and neither is their effectiveness.
  4. TTH

    TTH Senior Member

    Here is the September 1944 field manual for US Army assault gun (CS) platoons:

    Some notes:

    1. By 1944, in addition to the assault gun platoon, US Army tank battalions had three additional CS tanks (M4 Sherman with 105mm How), one at each tank company HQ. This gave a total of six, which I think is about the same number of CS tanks in a contemporary British armored unit. As US tank battalions were somewhat smaller, the proportion of CS tanks was somewhat higher than in British units.

    2. Sometimes all six US CS tanks could be grouped together to fire in battery.

    3. Enemy anti-tank guns and artillery were the primary targets for US CS tanks. Smoke was used "to cover gaps in smokescreens," which implies that the main job of laying smokescreens belonged to the field artillery.
  5. phylo_roadking

    phylo_roadking Very Senior Member

    Sheldrake - there was definitely an argument at the time of construction between the DTD and the Directory of Artillery....and it resulted in the Churchill Gun Carriers being given S-Numbers, not T-numbers...

    But it was resovled soon after and they were given T-numbers I.E. taken away from the RA.

    In his old CMV article on the Gun Carrier David Fletcher put the change as being from T to S....but there's an updated article in THIS onth's magazine...and it's definitely a change the OTHER way round - from S to T. So the RA lost them.

    He has a little more on the Gun Carrier's brief "service" and it's clear that from then on they were to be used in at least one (shortlived) role in an armoured unit.

    But there's no sign of the delay in production being due to the actual RA/RAC squabble; Fletcher DOES mention one reason for the delay, an absolute gem...

    Vauxhalls had never wanted to contemplate the project, but were ordered to go ahead...and nothing more was heard for six months. When someone went asking, Vauxhalls said that they'd been told that production was cancelled! Which of course it wasn't, not then at any rate... and there was a brief enquiry which couldn't find ANY trace of anyone having been in contact with Vauxhalls to cancel the project - and work was re-started. Months late of course...

    Looks like Vauxhalls tried to sweep the whole thing under the carpet in the hope that it would go away... :)
  6. idler

    idler GeneralList

    Tony56 has just posted links to a couple of training pamphlets. Two-thirds of the way down this page is:

    ROYAL ARMOURED CORPS WEAPON TRAINING Military Training Pamphlet No. 34, Part 7: Smoke, 1940

  7. phylo_roadking

    phylo_roadking Very Senior Member

    Very useful as to the process, not so much as to the tanks/guns themselves...but it DOES illustrate the importance and primary role of the CS tanks was for laying smoke - and points up the importance of the Close Support tanks' smokelaying role in relation to their parent formation.

    But looking ABOVE that pamphlet to the one on light tanks (and "light cruiser tanks"), where it's very specifically said several times that smoke candles are only for the protection of individual tanks if they encounter the enemy, not used to create a smoke screen as such as described in the "Smoke" pamphlet. That is, from the other pamphlet, indeed the job of the CS tanks.
  8. phylo_roadking

    phylo_roadking Very Senior Member

    I had a thought last week, and this is the first chance I've had to type it up...after having the thought reinforced by a number of comments in the M4 Sherman gun thread...

    In the course of this thread I got hold of a copy of the Churchill MkI manual including lading diagrams and lists of equipment stowed - and these clearly show that there were TWO spare sighting telescopes for the TWO inboard guns....one in the turret for the 2-pdr, and one in the hull for the 3in howitzer...

    ...and the spares were exacrtly the same item! I.E. the spare sighting telescope for the howitzer stowed down beside the hull gunner was the same telescope as that provided in the turret for the 2-pdr.

    In other words - they had the same graticule/reticule markings...for both purposes.

    What is the possibility that the howitzer round was "charged" so that when the howitzer gunner aimed at a point 1,000 yards, or 2,000 yards' away - according to the reticule - the howitzer smoke or HE round would...arrive...at the SAME point the 2-pdr's round would, when aimed at the same target at the same range?

    Just....via a higher-arching trajectory?
  9. idler

    idler GeneralList

    Went to Bovvy a couple of weeks ago and it wasn't all about the Tigers...

    The Churchill II gate guardian - supposedly the 3" CS howitzer but really bit of something else welded to a plate - compare the barrel thickness with one of the early photos in this thread:

    A10 CS - not sure if we can strictly call the Besa a coax as the main and secondary armament are offset:

    The 3.7" CS Mortar, bore and breech:
    IMG_0045-1200.jpg IMG_9744-1200.jpg IMG_9750-1200.jpg

    The 3.7" Howitzer breech for comparison (the old RA Museum). The barrel's also a lot thicker.

    The new Dick Taylor Book Firing Now! has some useful chapters on the CS weapons
  10. Seroster

    Seroster Canadian researcher

    Very interesting thread!

    I know I'm responding to a post from two years ago, but I just finished reading The Churchill Tank and the Canadian Armoured Corps, and was surprised we were involved in the use of the Churchill Gun Carrier. A unit was formed, 1 CATB Hvy Sp Coy (later renamed to a squadron). Formally created June 24 1942, did not receive any vehicles until Sept 1942 (5 converted Churchills), eventually broken up 15 Feb 1943.
  11. idler

    idler GeneralList

    Interesting to see someting on their 'tactical' employment. I wonder if there's a war diary that says whether they were intended for an antitank or direct HE support?
  12. Richelieu

    Richelieu Active Member

    It is perhaps worth mentioning for the uninitiated that the 3-inch weapon mounted in the Churchill Gun Carrier was an obsolete anti-aircraft gun rather than the 3-inch close support howitzer.

    The following Chiefs of Staff minute, which comes from TNA CAB 79/10/5, provides some background, and Mark Toner, the author of the book that Chris (Seroster) mentioned, has posted an excellent article on the Gun Carrier which references the war diary of 1st Canadian Army Tank Brigade Heavy Support Company.

    C.O.S. (41) 105th Meeting, 22 March 1941, 10:30 am.


    THE COMMITTEE were informed that the Defence Committee (Supply)+ had approved the conversion of 100 3-inch A.A. gun mountings for use with the U.P. Weapon.

    The War Office now suggests that the guns belonging to these mountings should be allotted for use in tanks. The Prime Minister had approved this suggestion subject to the concurrence of the Chiefs of Staff.

    SIR ROBERT HAINING [VCIGS] said that these pieces were of no use to A.D.G.B. and that he understood that there was no other requirement for them.


    Concurred in the suggestion that 3-inch A.A. guns should be allotted for use in tanks.

    + D.C. (S)(41) 3rd Meeting, Conclusion 1 (g)
    Seroster likes this.
  13. Richelieu

    Richelieu Active Member

    Phylo, while confirming that Ordnance Q.F. 3” Howitzer Mk.1 or Mk.1A were interchangeable with the 2-pdr, some papers on converting Matilda tanks to take the 3” howitzer at the NAA indicate that a change to Telescope Sighting No. 34 was required, or at the very least desirable. Perhaps the manual was the victim of some artistic license.

    See file: Matilda Tanks MP729/6, 51/403/421.
    Last edited: Jun 24, 2017
  14. idler

    idler GeneralList

    Based on not much more than this: British Sighting Telescopes could it simply be that the No.34 was a plain crosshair whilst the later No.30s were graduated?
  15. Richelieu

    Richelieu Active Member

    This is an area I know little about and I hadn’t seen that table before but something seems to be amiss to me. It says that the No.30 sight is for “Tanks with 2pdr, 15mm or 3" How + machine gun” i.e. a coax mount. If that’s correct then why were the Australians requesting No.34 sights from London when their Matildas would presumably already have been fitted with the No.30 sight? Also Phylo’s point remains: there would be a No.30 in a Churchill’s turret and a No.34 in its bow according to this table. www.wwiiequipment.com is usually pretty good so I’m not sure what to make of this.
    Last edited: Jun 25, 2017
  16. idler

    idler GeneralList

    Part of the problem is establishing which guns were shoulder-laid and which had elevation gears (at least for me, as I'm rather rusty). For shoulder-laid guns, it might make sense to have a graduated sight but the Profile for the Light Tank MkV states a plain sight with a range drum:
    Following his recent book on ammunition, there is perhaps scope for a Dick Taylor book on guns and sights...
  17. TTH

    TTH Senior Member

    Very interesting thread, even after three years.
  18. idler

    idler GeneralList

    It certainly doesn't show any signs of being solved any time soon... I did pull some files on smoke round tests for the 3.7" Mortar (then called the 15-pr 2cwt, tallying nicely with the contemporary 3-pr 2cwt gun) and need to have another look at them. In short, they were trialling a base ejection round and a bursting white phosphorus one. References to the latter as something like 'HE-charged' might have contributed to the 'myth' of the HE round? (Firing Now! does illustrate an HE round, in point of fact.)
  19. DavidW

    DavidW Well-Known Member

    Hi Idler.

    Sorry to come in late on this. Are you saying that there were no 3.7" HE rounds at this time?
  20. idler

    idler GeneralList

    I'd never claim there were none, that would be silly!
    I'm reasonably convinced that CS was applicable to 'armoured' units (not 'tank') and involved blinding threats with smoke - HE wasn't a doctrinal requirement. The smoke rounds appear to have been developed specifically for the Mortar, they weren't just reusing 3.7" Howitzer projectiles.
    However, Firing Now! has obviously found a source confirming an HE round, but there are still the questions of when and whether or not it actually madee it into the tanks.

    I'm suspicious that the 3" How could be a slightly different beast. It may have started life as a true CS 2-pr replacement and got HE later, or as a Char B inspired I-Tank requirement with HE from the outset. It's also possible that it was conceived to fulfil both roles, but that seems far too sensible in the context of the story!
    Last edited: Jun 25, 2017

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