Tanks in the pre-WW2 period

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The following text is an observation an analysis of mine without any claim of original thought. I believe it might still be of interest, for it puts many things together that are usually mentioned separately.

You may be interested in An analysis of late propeller era combat aircraft if you like this. Both texts are quite similar in their style.

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Let's pretend someone asked me whether this Guderian guy with his tank obsession is right, sometime in the early 1930's. I have the knowledge of 2012 available for the answer, without taking into account any post-1938 tank warfare.

First, I would ask for permission for a long answer.

If this permission is not given, I'd say "It depends."

If given, I'd say:

Well, let's look back why the Great War was such a mess in Europe.

It wasn't the machine guns, howitzers, trenches, large quantity of troops and barbed wire alone that produced the great mess, although a superficial look at it would suggest so.

First, all powers took at least two years to figure out how to break through such a defence. It was eventually understood and succeeded at high costs. Different approaches proved to be effective.

What was never understood was how to exploit such a breakthrough. Some powers sent cavalry to follow, but the cavalry encountered fire, had to dismount and fight understrength, as some cavalrymen always need to care for the horses. Once stopped, cavalry was even less capable to press on than infantry.

The British attempted to solve the issue with lightly armoured Whippet tanks of increased speed, but these machines were not good enough to press the attack very deep either, not the least because they ran into trouble once isolated from infantry.

Whippet tanks in Japanese service

The operational exploitation of breakthroughs was so extremely difficult because the defender could easily and quickly allocate reserves, mostly by rail but some also by foot march or on trucks. The attacker was simply too slow to succeed with narrow breakthroughs, and multiple breakthroughs as succeeded in 1918 led to an excessive expense of quality personnel and other resources.

The tank has in theory the capability to accelerate this attack. A tank crew can fight and even move on under machinegun fire, unlike cavalry - but it can cruise as quick as cavalry and be used for both breakthrough and exploitation.

This doesn't necessarily mean the tanks' success, for there's a response of the defence against tanks. Super-heavy machineguns such as the TUF or the .50" Browning heavy barrel machinegun can penetrate the usual tank armour plating and kill the entire crew within seconds [as of early 1930's]. Armour of at least about 30 mm thickness is necessary to protect against such machineguns.

13 mm TuF machine gun

Furthermore, dedicated anti-tank cannons can penetrate tanks more easily at greater distances with quick fire. Rheinmetall and Bofors have such 37 mm guns on offer and begun to export them to European and exotic countries. Armour of about 60 mm thickness or equivalent would be needed to protect against them, and that's so far only conceivable for front armour and at most turret sides, too.

Such defensive weapons are on the other hand not necessarily a death blow even to lightly armoured tanks if the crews are brave enough to assault against effective fire.A division might be asked to defend a sector of 10 or even 20 km width. Even a division at full strength with let's say 70 anti-tank guns and a similar quantity of large calibre machine guns would hardly stop a tank battalion under all circumstances. An even distribution without weak spots would yield only up to 7 guns and about 7 HMGs per kilometre. A terrain with short lines of sight - such as fields with thick flora or stone borders and 400 m width - would reduce the effective defence to only about three ATGs and three HMGs. These could easily be taken out with focused artillery fire once the line of defence was reconnoitered. The other anti-tank teams would only become effective after moving into new, less effective and survivable, positions and they might be caught during the movement.

Other schemes of defence are likewise imperfect. A focused tank attack can penetrate if well executed, the tanks don't even need to be particularly strong. Strength of armour allows for a greater portion available for the exploitation phase, though.

There's another problem, difficult to analyse in theory only. Defenders' reserves - again.

Air power can disrupt train movements and bring relief from quick strategic reserves intervention. Air power can hardly stop movements by truck, though. Trucks are not bound to rail roads and much more difficult targets - and trucks have become more available since the Great War.

The breakthrough and initiation of the exploitation phase would need to be extra quick in face of hostile truck-mobile operational reserves. It's feasible, but it requires skill, suitable hardware and strength.

Well, will tanks succeed? It depends.

Neubaufahrzeug tanks - German early 30's tank tech,
Bundesarchiv_Bild_183-L03744

Some tanks - especially the "infantry tanks" or "assault gun" concepts are a great help in the breakthrough phase and may under many circumstances even be a necessity for a successful or even quick breakthrough. Their use does not solve the final and most problematic problem of the Great War, though: The problems of the exploitation phase. A tank force built on such tanks alone would thus be no better than the British tank force of the Great War.

Very small and cheap tanks - tankettes - are not very promising either, for the ratio between volume and surface is poor and such tankettes end up having barely enough armour to withstand normal machine guns and carry light armament. The are worse than infantry tanks.

The operational exploitation tanks - Christie tanks, British cruiser tank concept, Guderian's tank idea - could be useful in the exploitation phase, but would suffer greatly if faced by suitable defences in the breakthrough phase or in mobile encounters with hostile reserves.

Finally, it's conceivable that a disconnect between slow and fast forces during the exploitaition phase leads to the encirclement and destruction of fast forces. Again, great skill and other conditions need to be met to avoid this from happening with a too high probability.

Last but not least, proper tanks are incredibly expensive, even in comparison to the already very costly heavy artillery such as heavy howitzers - even if we take their prime movers into account. The build-up and periodic modernisation of a sizeable tank force requires much economic strength. Tanks also consume a lot of fuel - about 10 litres per ton weight and 100 km. This requires adequate fuel supply, which could easily overextend the resource base of countries without much domestic oil production and limited or no access to foreign crude oil.

Even with hindsight, it should be rather astonishing that tanks became such a success in 1939 till 1942. The many historic failures of tank employment - including a failed Iranian attempt early in the Iraq-Iran War that saw Guderian-like ambitions fail due to lack of competence - point at how much has to come together for successful armoured warfare.

S Ortmann

related: About tanks, and why they're a necessity in modern ground forces
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