Appendix 8: A Note on Tanks, Armour and Anti-tank Guns
See photos 9 to 20
1. The second volume of this History contains an account (on page 174) of British and German tank production and some particulars (in Appendix 5) of the tanks and anti-tank guns in use in the Middle East up to the early autumn of 1941. The purpose of this Note is to summarize briefly the information there given and to bring it into line with the events of the present volume. The general position at the beginning of CRUSADER is stated on page 26 ff.
2. Explanation of terms and abbreviations used:
A shell is a projectile with a cavity filled with high explosive (HE) or smoke, and is usually fitted with a fuze. An Armour piercing (AP) shot is a solid projectile. Armour piercing capped (APC) is a shot or shell with a steel cap to prevent shattering on impact. A ballistic cap (BC) is a long pointed cap which helps the shot to maintain its velocity, and thus improves penetration at longer ranges. Homogeneous armour is armour of approximately the same composition and hardness throughout its thickness. The hardness of armour is its capacity to resist deformation; it is usually measured by the Brinell scale. Machinable quality armour (MQ) is homogeneous armour soft enough to be machined by ordinary commercial methods; its Brinell figure is less than about 400. Toughness is the capacity of armour to absorb energy before fracturing. Toughness and hardness are largely opposing properties, the relation of which has to be balanced. Face-hardened armour has a hard face, but a tough back.
German terms:
Panzerkampfwagen (Pzkw) or tank
Panzerabwehrkanone (Pak) or anti-tank gun
Kampfwagenkanone (Kwk) or tank gun
Flugabwehrkanone (Flak) or anti-aircraft gun
Panzergranate (Pzgr) or armour-piercing shell or shot
Pzgr 40 was a special light armour-piercing shot with a core of tungsten carbide.
3. Owing to financial stringency between the wars, and to a policy which for many years assumed that another major war was not to be expected, the British had allowed research and experiment on tanks to dwindle almost to nothing. When events compelled them to rearm they had no clear idea of the sort of war they might have to fight; there were demands for light and cruiser tanks, which seemed necessary for highly mobile warfare, and for ‘I’ tanks capable of acting against troops in fortified
positions. As war with Germany drew near, and the idea grew that it would be defensive in its opening stages, the emphasis on ‘I’ tanks increased. As a result of the campaign in France the British Army was practically disarmed; its losses included nearly 700 tanks and 850 antitank guns. The cry was now to rearm rapidly for home defence, for which purpose cruiser tanks, whose speed and mobility had been so well exploited by the Germans, were wanted in preference to ‘I’ tanks. But production cannot be switched about at a moment’s notice, and the choice was not between a good tank and a better one, but between a fairly good tank and no tank at all. The result was that some of the armoured divisions had to be rearmed with ‘I’ tanks. Similarly, it was decided to persist in the manufacture of the 2-pdr tank and anti-tank gun, even though this meant delaying the production of the 6-pdr.1 It took a long time to make up for these bad starts, and it was in the Middle East that the handicaps were most severely felt.
The Germans, on the other hand, had given the tank much careful study, and by 1939 they had four types in production, all thoroughly tested, and had even been able to try them out in the Spanish Civil War. In this way they had overcome the inevitable teething troubles. They had wisely allowed for larger weapons and heavier armour to be added if necessary, without interfering with the basic design, and they had standardized most of the parts and fittings so that they could spread manufacture over a large number of firms. When an alteration was wanted—as it was after the Germans had tested the British tanks and weapons captured in France—there was little delay in getting it done. They regarded the Matilda with respect; it was noted that she mounted a good gun, and that only the 8.8-cm Flak could penetrate her frontal armour.
4. Late in 1940 and during 1941 the Germans made three important changes in their equipment. They replaced the 3.7-cm tank gun by a short barrelled 5-cm, and began to replace the 3.7-cm anti-tank gun by a very efficient long barrelled 5-cm. They also increased the protection on their Pzkw III and IV medium tanks by adding plates of face-hardened steel at certain places. All Pzkw IIIs which came to North Africa mounted the larger gun but not all had the extra plates. It is not possible to tell what proportion of up-armoured tanks fought during CRUSADER, but subsequent examination of the battlefield suggested that there had been a considerable number.
The extra plates proved to have great power of resistance. The fact that they were face-hardened was not realized by the British until March 1942, when trials of the Grant’s 75-mm gun were being carried out against a captured Pzkw III. The discovery led to further tests. The plates were found to break up the 2-pdr uncapped shot at all ranges, and gave protection against the 6-pdr and the Grant’s 75-mm at anything over 500 yards. It was some consolation that after one or two hits the securing bolts (or more probably, studs) began to split or shear off.
The Germans, however, had not meant their extra plates to be anything but a stop-gap, and towards the end of 1941 they introduced
Pzkw III J and Pzkw IV Ft in which extra plates were dispensed with and the basic frontal armour was increased from 30-mm to 50-mm. A further surprise was in store for the British when they found that this armour also was face-hardened. These were among the tanks which began to arrive at Benghazi and Tripoli at the turn of the year and which fought in some numbers at Gazala.
5. The next step was to increase the gun power of both Pzkw III and IV. In the case of the III this was done by replacing the short 5-cm gun by the long-barrelled 5-cm which had proved so good in the anti-tank role. This model was the ‘III Special’, and began to arrive in time for the fighting at Gazala in May 1942. Pzkw IV was similarly up-gunned by having its short 7.5-cm replaced by a long 7.5, which made it formidable indeed. This ‘IV Special’ appears in DAK’s returns (this ‘outstandingly good’ tank) for the first time in June 1942, but only arrived in ones and twos. The gradual arrival of the Specials is shown by a few figures from the German records. Thus, the DAK had:
On 11th June: 110 IIIs of which 27 were Specials, and 14 IVs of which 6 were Specials.
On 27th July: 63 IIIs of which 16 were Specials, and 13 IVs of which 9 were Specials.
On 12th August: 135 IIIs of which 56 were Specials, and 24 IVs of which 16 were Specials.
On 30th August (the eve of Alam el Halfa): 166 IIIs of which 73 were Specials, and 37 IVs of which 27 were Specials.
The III Specials were still further improved by being fitted with ‘spaced armour’, of which the first example was found on a tank abandoned at Tell el Eisa after the fighting of 10th July 1942. It consisted of an extra 20-MM plate separated from the basic 50-mm armour of the gun mantlet and the front superstructure by an air space of four inches or more, and secured to it by long bolts. Its purpose was to destroy the Al’ cap and so reduce the power of a projectile to penetrate the plate behind.
6. All these improvements were examined on captured tanks, and the various types of plates were analysed and tested. The results of the tests for hardness, although they show considerable variation, explained the remarkable resistance of the German frontal armour.2 The British did not use hardened plate of such thickness themselves, nor had they the most suitable ammunition with which to attack it.
7. In addition to introducing new equipments the Germans made many improvisations, especially by turning existing guns (mostly captured) into self-propelled weapons, some for close support and others as anti-tank guns. First came the 4.7-cm gun of Czech manufacture mounted on a Pzkw I chassis, and then a few 7.5 mounted on 3-ton armoured half-track
vehicles. Another notable newcomer, prominent at Gazala, was the 7.62-cm Russian gun, of which the self-propelled version was mounted either on a 5-ton half-track vehicle or a tank chassis. This gun had better penetration than the 5-cm Pak and was a valuable addition to the German anti-tank defences; 117 had arrived with the Panzerarmee by May 1942.
8. On the British side, by July 1942 the obsolescent Matilda had been almost completely replaced by the Valentine, which, more reliable than the Crusader and faster than the Matilda, had to act both as a cruiser and as an ‘I’ tank.
The mechanical weaknesses of the Crusader were the subject of a special enquiry under Mr. C. R. Attlee in the spring of 1942. The finding was that
this tank had been pressed into production before the pilot model had been adequately tested. The situation had called for haste, and speedy production was essential; it had been obtained at the cost of mechanical reliability and fighting efficiency.
In July 1942 yet another complaint against the Crusader was made by the Middle East, who had been comparing Grant and Crusader casualties.
While the latter’s hull and turret were found to have been repeatedly holed by 5-cm projectiles, the former had stood up well to these; most penetrations had been made by 7.62 or 8.8-cm projectiles. Firing trials were then held against Crusader II, which was found to give much less protection than had been expected of a tank on a ‘50-mm armour basis’.3 This was bad, for it was important that crews should have confidence in the armour of their tank.
9. By May 1942 the American Stuart tank, previously employed as a cruiser, had come to be treated as a light tank suitable for reconnaissance and observation work. (The Americans had never regarded it as anything but a light tank.) The Grant was welcomed as a great advance on the Crusader. It had defects, such as its lack of speed across country, the restricted arc of fire of its 75-mm gun mounted in a sponson at one side, its delicate sighting gear, and the tendency of the gun mantlet to jam. The armour, however, was excellent and the crews had great confidence in the tank. Its 75-mm gun was not primarily an anti-tank weapon, being a standard American field gun with a good HE performance. It thus corresponded more to the short 75 carried by the Pzkw IV. The Grant carried also a 37-mm high-velocity gun in the turret, similar to the Stuart’s, so the position was that the 75 could engage targets with HE shell or with a moderately good AP shot at much longer ranges than could the 37 with its good, though small, APCBC shot.
10. This matter of different types of ammunition was of great importance. A few close-support ‘I’ tanks and Crusaders could fire HE or smoke from their 3-inch howitzers, but the Grant was the only tank to fire both HE and AP, which gave it the means of countering not only tanks but also anti-tank guns. The AP shot fired by the British 2-pdr and 6-pdr, and by the 75-mm on the Grant, would have been more use
against face-hardened armour had they been capped. But only the 37-mm shot was fitted with both piercing and ballistic caps, which gave it a slightly better performance than the 2-pdr against face-hardened armour. The 25-pdr was provided with a proportion of uncapped AP shot, as was the 40-mm Bofors, which was primarily an anti-aircraft weapon.
The German policy was to provide different natures of ammunition for nearly every gun, so that it could be used in more than one role. For example, the 8.8-cm was supplied with time-fuzed HE for anti-aircraft work, with percussion-fuzed HE for field targets, and with base-fuzed AP shell with piercing and ballistic caps for attacking armour. Similarly the small 2-cm, nominally a flak gun, was expected to take on aircraft, armoured cars, light tanks, machine-gun nests, lorries or troops on the move. The tank and anti-tank guns (3.7-cm, 5-cm and the Russian 7.62-cm) all had HE and capped armour piercing, and a small quantity of ‘Pzgr 40’. This was a special high velocity shot, commonly called ‘arrowhead’, effective against armour at short range; as will be seen from the table on p. 443 its performance fell off badly at longer ranges. By the summer of 1942 the Germans had introduced ‘hollow charge’ ammunition for their low-velocity weapons. Unlike the usual AP projectile this depended not upon the force of impact but on controlled explosive action, and was intended to provide their infantry guns and field howitzers with some means of attacking armour plate. It also improved the AP performance of the short 7.5-cm Kwk.
The British had naturally been anxious to devise some method of increasing the power of the 2-pdr gun, while awaiting the arrival of the 6-pdr. A new High Velocity shot was introduced in small quantities in the summer of 1942, but being uncapped it suffered from shatter. More promising was the choke-bore ‘Littlejohn conversion’, but this had to be re-designed when the Germans were found to be using spaced armour and was not in time to be used. The Royal Army Ordnance Corps’ Base Workshops and Ammunition Depots in the Middle East were not equipped to fit caps to 2-pdr shot, but they made a brave effort to meet the deficiency in capped 75-mm ammunition by adapting captured German APCBC shell for use in the Grant’s 75-mm gun. Encouraged by a highly satisfactory trial they lost no time in converting some 15,000 rounds and rushed them up to the 8th Army about the end of May. Thereafter the story is less clear, but it seems that, for one reason or another, little use was made of this composite ammunition which had so ingeniously been made available.
The Middle East were very worried about the time taken to match the improvements made by the Germans, let alone get ahead of them. They urged that the 6-pdr should be provided with the best possible ammunition, but were told that, although this was in hand, neither piercing nor ballistic capped shot would be available for the 2-pdr and 6-pdr until 1943. The position with the Grant was more encouraging, because tests of the APCBC projectile (M61) in the Middle East showed that it could penetrate the Pzkw III’s 62-mm plates at 1,000 yards. This ammunition was not available until after the battle of Alam el Halfa.
Thickness in Millimetres of some of the plates on British, German and Italian Tanks
The number of degrees shows the inclination of the plate to the vertical. Where no inclination is given the plate is vertical.
British
| Type | Hull | Superstructure | Turret | Remarks | |||
| Front nose plate | Sides | Front Glacis plate | Driver’s front plate | Front | Sides | ||
| Crusader II | 33* at 29° | 28 | 20 at 60° | 40 | 49* at 7° | 24 at 45° | * Figures for Mark I were 27 and 39. |
| Valentine II | 60 at 21° | 60 | 30 at 68° | 60 | 65 rounded | 60 | |
| Matilda II | 78 rounded | 40* | 47 at 67° | 75 | 75 at to° | 75 | * Plus a 25-mm skirting plate. |
| Stuart | 44 at 25° | 25 | 16 at 66° | 38 at 12° | 38 at 12° | 32 | |
| Grant | 50 rounded | 38 | 38 at 53° | 50 at 30° | 57 rounded | 57 rounded | |
German
| Pzkw III Model H | 30 + 32 at 52° | 30 | 25 at 84° | 30 + 32 at 9° | 30 at 15° | 30 at 25° | See footnote’ |
| Model J | 50 at 52° | 30 | 25 at 84° | 50* at 9° | 30* at 15° | 30 at 25° | *Sometimes 20-mm spaced armour added. |
| Model L | 50 at 52° | 30 | 25 at 84° | 50 + 20 at 9° | 57 + 20 at 15° | 30 at 25° | Spaced armour is standard. |
| Pzkw IV Model E | 50 at 12° | 20 + 20 | 20 at 73° | 30 + 30 at 10° | 30 at 11° | 20 at 26° | |
| Model F (t and 2) | 50 at 12° | 30 | 25 at 73° | 50 at 10° | 50 at 11° | 30 at 26° |
* It is probable that extra plates were fitted to some tanks of earlier models also.
Italian
| M 13/40 | 30 rounded | 25 | 25 at 81° | 30 at 11° | 40 at 16° | 25 at 22° | The armour on M 14/41 was practically the same. |
Some particulars of British and Enemy tanks 1941/42
British
| Type | Weight tons | Crew | Main armament | Type of ammunition | Secondary armament* | Thickest armour (see also previous table) | Engine BHP | Cross-country speed mph† | Remarks |
| Cruiser A 13 | 14.75 | 4 | one 2-pdr | AP shot | one .303-inch m.g. | 30-mm | 340 | 12 | 62 of these were in 7 Armd Bde on 27th November 1941. |
| Crusader Mark II | 19 | 4 | one 2-pdr | AP shot | one 7- 92-mm m.g. | 49-mm | 340 | 12 | The close-support tank was armed with a 3-inch howitzer firing HE or smoke to a max. of barely 2,000 yards. |
| Matilda Mark II | 26.5 | 4 | one 2-pdr | AP shot | one 7.92-mm m.g. | 78-mm | 175 | 6 | ditto |
| Valentine Mark II | 16 | 3 | one 2-pdr | one 7.92-mm m.g. | 65-mm | 131 | 8 | ||
| Stuart Mark I | 12.5 | 4 | one 37-mm | APCBC shot | two .30-inch m.gs. | 44-111111 | 250 | 15 | American tank also known as the ‘Honey’. |
| Grant Mark I | 28.5 | 6 | one 75-mm (in sponson) one 37-mm (in turret) | 75-mm AP shot and HE, 37-mm APCBC shot | one, two or three .30-inch m.gs. | 57-mm | 340 | 10 | The Grant was preceded by the Lee which was almost identical. |
German
| Type | Weight tons | Crew | Main armament | Type of ammunition | Secondary armament* | Thickest armour (see also previous table) | Engine BHP | Cross-country speed mph† | Remarks |
| Pzkw III Model H | 20 | 5 | one 5-cm (short) | APCBC, Pzgr 40 and HE | two 7.92-mm m.gs. | 62-mm | 300 | 11 | |
| Pzkw III Model J | 22 | 5 | one 5-cm (long) | APCBC, Pzgr 40 and HE | two 7.92-mm m.gs. | 50-min | I y | 12 | |
| Pzkw IV Model E | 22 | 5 | one 7.5-cm (short) | APCBC, HE and hollow charge | two 7.92-mm m.gs. | 60-mm | f , | 10 | |
| Pzkw IV Model F2 | 23-25 | 5 | one 7.5-cm (long) | APCBC, Pzgr 40, HE and smoke | two 7.92-mm m.gs. | 50-mm | >7 | to |
Italian
| M 13/40 | 13.5 | 4 | one 47-mm | AP and HE | three 8-mm m.gs. | 40-mm | 105 | 8 | M 14/41 was an improved version with a 525 h.p. engine. |
| M 14/41 | 14.7 |
* MGs carried for AA purposes are omitted.
† Speed across country is greatly affected by the surface. These figures are a guide to comparative speeds in the Desert.
Tank and anti-tank guns
Expected penetration in millimetres of homogeneous armour plate
An angle of impact of 30° to the normal has been taken simply as a basis for comparison. In battle the angle of impact may be anything from o° to 90°. As a rough guide it may be taken that at short ranges the penetration of a shot striking normally to the surface would be about one and a quarter times that of the figure given for 30°. At 60° it would be rather less than half.
Further work on captured German documents has led to some revision of the figures given in Appendix 5 of Volume II of this History. It is still necessary, however, to point out that while the figures give an idea of the relative expected performances of the various projectiles, they cannot be taken as a definite forecast of how any one particular shot or shell will behave.
British
| Weapon | How moved or mounted | Weight of shot or shell(lb.) | Muzzle velocity (feet per second) | 250 yds. | 400 yds. | 500 yds. | 750 yds. | 1,000 yds. | 1,500 yds. | 2,000 yds. | |
| 2-pdr | Towed or portée; and tank gun of Crusader, Matilda and Valentine | 2 AP shot | 2,600 | 58 | — | 52 | 46 | 40 | — | – | |
| 6-pdr Mark II | Towed or portée | 6.25 AP shot | 2,675 | — | — | 79 | 72 | 65 | 52 | – | |
| 25-pdr (not primarily an anti-tank gun) | Towed | 20 AP shot | 1,550 | — | — | 63 | 58 | 54 | — | – | |
| 37-mm | Turret of Stuart and Grant | 1.92 APCBC shot | 2,900 | 58 | — | 53 | 48 | 47 | — | – | |
| 75-mm M 2 | Sponson of Grant | 14 AP shot | 1,930 | — | — | 61 | — | 53 | 46 | 18 | |
German
| Weapon | How moved or mounted | Weight of shot or shell (lb.) | Muzzle velocity (feet per second) | 250 yds. | 400 yds. | 500 yds. | 750 yds. | 1,000 yds. | 1,500 yds. | 2,000 yds. |
| 2.8-cm s.Pz.B.41 (tapered bore 1.1/0. 787-in.) | Towed or lorry-borne | .28 composite non-rigid shot | 4,600 | (50) | 41 | 36 | 30 | — | — | – |
| 3.7-cm Pak 35/36 (L/45) | Towed or lorry-borne | 1.5 APC shell | 2,500 | 32 | 29 | 28 | — | — | — | – |
| 0.78 Pzgr 40 | 3,378 | 40 | 32 | 28 | — | — | — | — | ||
| 5-cm Kwk (L/42) | In Pzkw III H and early J | 4.5 APCBC shell | 2,240 | 56 | — | 53 | 46 | (40) | — | – |
| 1.94 Pzgr 40 | 3,440 | 83 | — | 60 | 42 | — | — | – | ||
| 5-all Pak 38 | Towed | 4.5 APCBC shell | 2,700 | 67 | — | 61 | 56 | 50 | — | – |
| 5-cm Kwk 39 (L/60) | In Pzkw III J Special and L | 1.94 Pzgr 40 | 3,930 | 109 | — | 77 | 46 | — | — | _ |
| 7.5-cm Kwk (L/24) | In Pzkw IV E and F 1 | 14.9 APCBC shell | 1,350 | — | — | 46 | 42 | 41 | — | – |
| 9.75 hollow charge | 1,476 | about 75-mm irrespective of range | ||||||||
| 7.5-cm Kwk 40 (L/43) | In Pzkw IV Special F 2 | 15 APCBC shell | 2,428 | — | — | 89 | — | 79 | 70 | 62 |
| 7.62-cm Pak (R) | Towed. SP version on 5-ton half-tracked lorry | 14.81 APCBC shell | 2,165 | — | — | (79) | — | (70) | (61) | (53) |
| 9.25 Pzgr 40 | 2,789 | — | — | (84) | — | (68) | — | – | ||
| 8.8-cm Flak 36 (L/56) | Towed on trailer 201 | 21 APCBC shell | 2,600 | — | — | 112 | — | 103 | 92 | 83 |
Figures in brackets are estimated.
All the above German weapons were also provided with a HE shell, slightly lighter in weight than the AP projectile.
The figures under the German guns give the length in calibres.
Italian
| Weapon | How moved or mounted | Weight of shot or shell (lb.) | Muzzle velocity (feet per second) | 250 yds. | 400 yds. | 500 yds. | 750 yds. | 1,000 yds. | 1,500 yds. | 2,000 yds. |
| 20-mm M/35 Breda | Towed | 0.308 AP shot | 2,750 | 29 | 27 | 24 | — | — | — | – |
| 47/32 (Model 37) | Towed. Also gun of M 13/40 and M 14/41 tanks | 3.25 AP shell | 2,060 | 48 | — | 38 | 32 | — | – |