WW2 New Zealand Armor

Mills’ Travelling Motor Fortification and Charging Device / Rapid Travelling Armour Clad Field Fortification

New Zealand (1914-1915)
Moving Fortress – None Built

In the history of the development of the modern tank in WW1, a lot of people are aware of the Landships Committee and names like Stern, Swinton, and Tritton – names synonymous with the invention of the tank. Fewer people are aware of Lancelot de Mole, an Australian inventor who had submitted a tracked vehicle design which was ahead of its time and represented a lost opportunity for those developing the first tanks in Britain in WW1. Almost unknown until now are some of the inventors of the ideas which never got taken seriously. One unnamed antipodean inventor had his invention submitted by a friend to the British military before the formation of the Landships Committee in February 1915; Mr. E.C.Evelyn Mills. Whether Mills’ was writing from a ‘friend’ to mean himself or genuinely on behalf of another is not known but this whilst this person’s ideas may seem naive now, especially in light of over a century of armored warfare experience which followed, this 1914 concept was, if anything, modest. As Mills failed to name his friend and was asking for a substantial sum of money it is perhaps more likely that he was simply writing on behalf of himself. Consigned to being forgotten by history, all that is left of Mr. Mills’ work lies in just three surviving pages of text in the files of the British Ministry of Munitions. What they contain though is a rare glimpse into an early idea for armored warfare and one which, unlike De Mole, has had no recognition until now.

First Contact

On 16th October 1914, Mr. E.C. Evelyn Mills wrote from the Royal Colonial Institute, Northumberland Avenue, London, to Lieutenant Colonel G.N.H. Barlow, an experienced artillery officer. Mills had designed with the assistance of an unnamed friend a vehicle for defeating “the atrocious Prussians”. Lt. Col. Barlow thankfully did not discard the unusual idea from Mr. Mills, but instead passed it on to Col. Louis Jackson, a retired officer of the Royal Engineers. Col. Jackson would later return to service as a General and serve as the head of the Trench Warfare Research Department at the Ministry of Munitions. Col. Jackson then wrote to Mr. Mills, but it was not until 22nd April 1915 that Mills provided more technical information outlining his idea.


One of the key defining problems in the early days of the development of what became known as tanks was what role they were to perform. In 1915, this had started for the Landships Committee as a means to transport a large party of men, protected from German machine-gun fire, over broken ground covered with barbed wire. Effectively, this was what would be known in modern terms as an Armored Personnel Carrier but, in 1915, there was no such name. Later, these carriers changed in role to a vehicle intended for the destruction of enemy machine-gun emplacements instead. In 1914, when Mills submitted his idea, these vehicles were still a long way away both in concept and technology.

Without words such as ‘tank’ with which to name his vehicle, Mills simply defined his new vehicle as a “travelling Motor Fortification and Charging Device” in his initial letter and then, in a follow-up, as a “Rapid Travelling Armour Clad Field Fortification”. Both names give a very clear impression as to what it was that Mills was intending for use from his vehicle. Primarily, the vehicle was to be used to screen soldiers from enemy fire by providing a large mobile shield or “breastwork” for up to 200 soldiers, although, in his April 1915 letter, he changed it to provide cover for 150 men instead.

Mills envisaged a novel form of attack, with some unnecessarily complex ideas for moving the vehicle forwards and backward almost randomly to make targeting by enemy gunners much harder. As the vehicle advanced, it would plough over and through enemy positions, leveling them for the men following. It would advance over enemy trenches up to 10’ to 12’ (3.05 to 3.66 m) wide, a figure more than double the expected 5’ (1.52 m) trench which was set out for the Landships Committee later in 1915. Having crossed the enemy trenches, the vehicle could then turn to follow the lines of enemy defences to clear them of enemy troops but it could also directly assault an enemy gun by charging it and would not have to turn around in order to withdraw from combat. Further to this ‘charging’ idea, the vehicle was also supposed to be able to be used “as a conduit or ram for attacking a Fort, running right up to a wall. Mining or attacking and discharging any kind of explosive, bombs etc, bursting up wall of Forts etc”.

Following the attack on the enemy, the vehicle could also be used to carry wounded troops to the rear or even be used as a transporter for stores and supplies. The internal space was seen as being large enough to accommodate 2 or 3 field guns or military wagons.


As well as the rifles of the 200 men being carried by this vehicle, Mills also foresaw fitting it with “quick firing machine guns” on the front and sides as well as “larger guns” which were unspecified. Altogether, the firepower for the rifles, machine guns, and ‘larger guns’ across the sides would provide the design with what Mills’ claimed would be a “fearful broadside”.


Sadly, there are no sketches available from Mills’ to show what his vehicle was to look like. If he had sent sketches in with his original letter of 1914, those are now lost, but as none were mentioned in the letter it would appear that there were probably not any at that time. In April 1915, Mills was only suggesting that drawings would be provided if the scheme was approved, which once more suggests that although he may have some sketches none were sent in with the April letter. Again, if any were actually sent in they were not retained with the letter and are now lost. Without those, it is impossible to know exactly how Mills saw his design but he provides sufficient information in his description of the vehicle on which to make a reasonable estimate as to what it may have looked like.

Heavily sloping armor plating across the front, top, sides, back, and bottom was sufficient to stop enemy bullets from injuring the 150 to 200 men inside the vehicle. In 1914, this would have likely resulted in 8 mm to 10 mm of bulletproof plate which was considered adequate prior to the use by the Germans of ‘reversed’ or steel-cored bullets. The sides were to have 120 rifle ports on each side and another 20 or so at each end with a steel or iron shelf for marksmen to lie on when firing, a total 280 loopholes.

Although Mills did not specifically mention side or rear armor, he did allude to it in discussion of the armament and fightability of the design, leaving no doubt that the vehicle was to be completely covered in armor. What is very unclear, however, is his intention that the armor plating should be “hinged and formed [so] that it [the vehicle] can be run into a river with others of its kind and form a continuous Bridge for troops, wagons, artillery, cavalry &c [etc.] to pass across water courses etc.”

With the description of it as a ‘conduit’ as well as a bridge, it would appear that Mills’ design was likely a relatively straightforward box shape rather akin to a medieval siege tower laid on its face and driven forwards. One complicating factor is the description that the vehicle would be able to travel over obstacles up to 8’ (2.44 m) high passing through the vehicle. There is no mention of ground clearance and he provided the dimensions as approximately 37’ (11.28 m) long x 22’ (6.71 m) wide x 11’ (3.35 m) high. If it could traverse an 8’ (2.44 m) diameter obstacle down the middle of the vehicle, this would leave just 3’ (0.91 m) to the roof of the vehicle – not even enough space to sit in. Mills describes the interior fittings as ‘shelves’ though indicating that, rather than having a floor, his design seems to simply forgo the floor and have the man stand or lie on platforms along the sides and inside the front and back. This arrangement would mean that the doors at the front and rear would be upward opening making much clearer how it could work as a bridge, although it would mean that the observation tower would presumably have to be off to one side so as not to prevent troops, horses, guns, etcetera from crossing over the roof.

With doors at the front and back, this would allow the hollow floorless-box to act as the conduit he planned and fitted with a large folding door at the front would allow it to discharge troops for assaulting a position. Mills was also careful to make clear that there was enough space inside to provide a shelter for a 12 lb. gun with its 24’ (7.32 m) gun carriage with enough space for firing.

The unusual arrangement is actually reflected in the early work on the Pedrail landships in 1915 which had also involved consideration of troops carried in a sort of ‘corridor’ along the sides of the vehicle behind armor. For the Pedrail landships, that method of carrying troops was estimated by Colonel Crompton (the contracted expert engineer on the committee) to require 0.49 m2 per man. Mills’ vehicle would (assuming a single-tier floor area on each side) have a floor area of more than double that on the Pedrail landship at 48.17 m2. At 0.49 m2 per man this would provide space for up to about 100 men. Assuming that the 3’ (0.91 m) high area over the central portion of the vehicle could be used for a man lying prone, this would increase the ‘floor’ area of the vehicle to 75.69 m2. A lying man takes up more space but estimating that space as four-times the space of the standing man, this would add a further 13 or 14 men to the total capacity and this may be the ‘shelf’ to which Mills referred. Neither of those floor area figures, however, account for the space which would have to be taken up by the motors, fuel tanks and other components to propel it.

This would perhaps explain the ‘bridge’ idea too, as it would need only be driven into the river and use its hollow shape to create a covered bridge.

At the front and back end of the vehicle was a plough with the intention that this would destroy enemy defences such as earthworks, allowing troops behind to pass through. The vehicle was to be fitted with a wireless telephone for communications. A key feature of the design was the use of a pneumatic telescopic lookout tower 60 (18.29 m) to 100 feet (30.48 m) high, fitted with a searchlight.

Mills’ foresaw an ideal speed as being about 20 to 25 mph (32 – 40 km/h) and estimated (very optimistically) that each vehicle would cost between ‎£4,000 and ‎£5,000.

Power for the vehicle was supposed to come from a pair of 120 hp ‘Daimlers’, which, for a total estimated weight of just 18.5 tons (18.80 tonnes), would mean a power to weight ratio of 6.38 hp/t. This was surely highly optimistic bearing in mind that even Colonel Crompton’s wheeled fort design of February 1915, which was substantially smaller, was going to weigh 24.7 tonnes fully laden with men and guns. Based on this, it seems likely that the weight estimate from Mills’ was far too low and would likely be nearer 30 tonnes, rendering it significantly less mobile than what Mills was proposing.

As the design was effectively two fighting-halves connected by a roof, it appears likely that Mills envisaged one engine on each side driving the wheels. This system would have the significant advantage that the wheels would not have to turn to facilitate steering and it would rely on the skid-steering principle, with direction being affected by varying the throttle to the engine on one side over the other, rather like the way the Medium Mark A ‘Whippet’ was steered. Without actual plans of the vehicle or an explanation of how it was to be done though, this arrangement and method of steering is speculative.

Mills’ vehicle idea had some clear rationale behind it but, as an idea, it was still fundamentally flawed. Despite whatever benefit this engine arrangement may have brought, the vehicle was still wheeled and not tracked. Mills never specified how many axles of what size there were meant to be on the vehicle. The only data provided about the wheels is that they were to have a track width of 10’ (3.05 m), which is the distance between wheels along their axle.

Wheels would mean it was going to create a very high ground pressure under each wheel and that even with multiple wheels it would still produce an excessive loading on a soft surface.

Who was E.C. Evelyn Mills?

The clue to identifying E.C. Evelyn Mills is that he wrote in from Royal Colonial Institute, Northumberland Avenue, London. A check of various registers and legal documents of the period finds that, in 1902, Mr. E.C. Evelyn Mills was the owner of an 1898-built, 15-ton Australian yacht called ‘Rainbow’ registered in Wellington, New Zealand to a local yachting club. This would certainly help to explain some of the features and descriptions, like the tall mast with searchlight, and use of nautical terminology, respectively. The NZ records are also supported by the electoral records from the Royal Colonial Institute in London, showing Mr. E.C. Evelyn Mills of Wellington, New Zealand was first elected there in 1896. Their journal, ‘United Empire’ (1915), also shows that Mr. Mills was elected as a Member of the War Services Committee there in mid-November 1914, which would likely explain his interest in a new type of war machine. Following Mills to New Zealand shows that his full name was Edward Charles Evelyn Mills, born 1857 and died 14th June 1916.

Mills as a character appears to have been reasonably well to do. He has subscribed to contribute money to the war effort yet no doubt he was optimistic after the contact with Col. Jackson about his ideas. Mills even offered to superintend the construction of his own machines for Col. Jackson for the modest fee of 20%. Using his estimate of ‎£4,000 to ‎£5,000, this would have meant a commission of ‎£800 to ‎£1,000 per vehicle.


This design from Mills sounds very similar to the role fulfilled by the first tanks in 1917, smashing their way through enemy wire fortifications to allow troops to follow, but it was also meant to be carrying troops like an armored personnel carrier. Further, it was meant to directly assault gun positions and even forts like an ‘assault’ or ‘heavy’ tank and also to be able to form a bridge-like an AVLB (Armored Vehicle Layer Bridge). So what was Mills’ vehicle? His description as to the possible uses for it covers almost every type of military vehicle from engineering vehicle to tank to ambulance and are really symptomatic of a lack of understanding as to the utility of armored fighting vehicles and of many of the problems with actually fielding such a weapon.

Nonetheless, this vehicle was suggested before there was even a Committee (the Landships Committee) formed to develop a tracked machine. He did not, however, send in a completed idea until the end of April 1915, by which time the Committee had already started work and such ideas as Mills’ were already obsolete. As such, his ideas were simply filed away and forgotten about. Mills died before he ever got to see tanks used by Britain and obviously was not around to even apply for recognition post-war as so many others did. His ideas might have been naive and he might not have lived to see the first use of tanks, but Mills deserves to be recognized as one of the exclusive group who was advocating for armored vehicles in those early years of WW1.


Dimensions (L-W) 37’ x 22’ x 11′ (11.28 x 6.71 x 3.35 meters)
Men Carried 150 – 200
Trench 10 to 12’ (3.05 to 3.66 m)
Total weight, battle ready 18.5 tons (18.80 tonnes) more likely ~30 tonnes
Propulsion 2 x Daimler 120hp
Speed 20 to 25 mph (32 – 40 km/h)
Armor Front, Top, Bottom sufficient to stop bullets ~ 8-10 mm thick


Letter to Col. Barlow from E.C. Evelyn Mills, 16th October 1914
Letter to Col. Jackson from E.C. Evelyn Mills , 22nd April 1915
Lloyds Register of British and Foreign Shipping (Yacht Register) 1902-1903. London, UK
Proceedings of the Royal Colonial Institute, Vol. XXXIX, 1908. London, UK
United Empire, Vol. VI Series I. January 1915. London, UK
New Zealand Times, Vol. LII, Issue 9309. 2nd June 1891 ‘Marriage’
Royal Colonial Institute Year Book 1915. London, UK
Press, Vol. L, Issue 15129 19th November 1914, ‘New Zealand War Contingent Association’
New Zealand Herald, Vol.LI, Issue 15767, 16th November 1914 ‘Expeditionary Force’
Hills, A. (2019). Col. R. E. B. Crompton. FWD Publishing, USA

WW2 Australian Prototypes WW2 New Zealand Armor

Wentworth Cruiser Tank

Commonwealth of Australia/New Zealand (1924-1942)
Cruiser Tank – Drawings Only

War can bring about a wide variety of ideas from an equally wide variety of people and places, and one design from Australia came from the most unlikely of places; a prison.
The person concerned in this unusual tale is Prisoner ‘131’ – Jack Alva Heeney – who was, in April 1942, residing at his Majesty’s pleasure in Maitland Gaol, New South Wales, Australia. Heeney, a fitter by trade, was 52 in 1940 and serving a lengthy sentence. Heeney wrote from his cell to the Australian Army Inventions Directorate regarding a Cruiser tank he claimed to be of his own design, which he also claimed was already in the possession of the British War Office.

Maitland Gaol, New South Wales. Photo:
Heeney declared himself to be a former ANZAC (Australia and New Zealand Army Corps) who had served until 1918, participating at the Gallipoli landings and claimed to have invented a type of bomb-thrower used on ‘Walker’s Ridge’ fighting the Ottomans. Later, he said, he had served in “the China Conflict”, although his interest in tanks was spurred by time spent in France. Heeney further claimed that following the Civil War in Spain he decided to pursue his tank design further as he had, he stated, spent the 18 years preceding his letter (~1924) studying on-and-off improvements to “the War Tank” and that it had even been tested in at Charters Towers, Queensland, in 1936, although this seems extremely unlikely.
Heeney further claimed to have already submitted the design to the War Office in Great Britain, but that due to a shortage of funds they could not finish his design so relented until 2 months prior to the start of WW2 when he claimed the War Office wrote back to him for his idea offering to pay his expenses. Heeney, though, without a cash guarantee from the War Office stated that he declined to attend the War Office and instead wanted to offer the design to the Australian office.
Perhaps to emphasize how important and valuable this design was, Heeney claimed a man had tried to shoot him for them in 1937.
Heeney, does, however, provide a short description of his tank in his initial letter stating that it could dig trenches and bury itself completely. Fitted with four turrets “of the latest design” and that it was completely protected against poison gas. What is very odd in this letter, other than the obvious attempts to extract money from the recipient, is that Heeney claims there to be ‘seven secrets on this tank’ and that he also offered the Australian Army the design of the German ‘Star Fish Bomb’ which he claimed to have been stolen from Germany in 1924 saying explicitly that this bomb “was made to deal with the tank”. This does beg the question of quite how secret, novel, inventive, or ‘of the latest design’ this vehicle could really be, leading to a conclusion that Heeney may simply have been trying his luck with the War Office. A fact reinforced by his statement that his wife had already spent £800 (about £36k to £47k in 2018 values) on this tank and that “my people in New Zealand have interests” in it.
As a result of this letter though, a representative from the Army Inventions Directorate attended Maitland Gaol in June 1942 to interview Prisoner Heeney. During this interview (conducted with the permission of the Governor) it was revealed the Heeney planned to mount a 25-pounder gun in his design and that “a firm in Newcastle was willing to construct a tank of this type”. With just three months of his sentence left he would be free by October 1942 to pursue this outside the confines of the gaol. His proposal was that upon completing his sentence that he should collaborate with this unnamed firm in Newcastle on his design with the blessings of the Army.
Heeney provided the Army with sketches and specifications of this design which “is capable of digging itself in so that it does not become a target” and this information was forward up the chain of command in the Directorate.
The submission was rejected by July that year though as “nothing in this worthwhile referring to A.F.V. P.” and the original papers and sketches were returned to Arthur Griffith (Mr. Heeney’s Patent Attorney), although no patent for the design seems to have ever been filed.
Mr. Heeney, whose occupation was given as ‘blacksmith’, was, by June 1942, in the Army files, noted to have arranged a partnership with the firm of W.A. Miller, King Street, Newcastle for the construction of a prototype of his machine and the description provided at the time was:

“25 pounder gun, Turtleback, swivel to rear if necessary. Shielded radiator, ½” steel [12.7 mm]. Detachable track. Convert to Mobile Car”

The description then is more akin to the convertible wheel-cum-track Schofield tank from New Zealand than any British Cruiser, and whilst the 12.7 mm (½”) steel armor was not impressive, it would certainly be sufficient to keep out bullets and shell splinters. The 25 pounder gun though, is the really interesting part. The official Australian tank production development program had planned to mount this powerful gun in a tank as early as December 1941 but did not actually do so until the first half of 1942. Mr. Heeney was, therefore, absolutely up to date with some ideas about up-gunning tanks for the war effort. This gun would have been very well suited to fighting the particularly thinly armored Japanese tanks of the era and for supporting the infantry, although, in the end, the 25 pounder armed Cruiser would never be adopted; an opportunity missed for Australia. As such, one has to give credit to Mr. Heeney for consideration of this weapon for his design regardless of how realistic the design may or may not have been.
By October 1942 and the time of his release from Maitland Gaol, Heeney was claiming to have spent some 14 years of study developing the design (rather than the 18 years he had claimed earlier in his correspondence). The design had not been patented as he claimed as he was waiting for some interest before doing so, as the filing would cost him £7, 7 shillings. He had, however, engaged a reputable firm of patent attorneys to act on his behalf and stated that the plans and arrangement to build the machine were ready to go.

Artist’s impression of Wentworth’s Cruiser tank based on his description.

Artist’s impression of the trenching conveyors at the front of the tank.
These illustrations were produced by Mr. C. Ryan, funded by our Patreon Campaign.

His name

The name and identity of the designer/inventor warrants examination as the inmate submitting the design is given as Prisoner 131 – Jack Alva Heeney – but in some correspondence, he is referred to as ‘T. Heeney’ instead. In his June 1942 interview, the Army lists him as Mr. Jack Alva Wentworth using the name Heeney and note calmly that he was currently serving a sentence for 12 charged of False Pretences, Larceny as Bailee, Forging and Uttering in New Zealand 1942.
Those charges are confirmed in the 3rd January 1940 edition of The Evening News (Queensland) where ‘Jack Alva Wentworth’, aged 52, pleaded guilty to 8 charges of false pretenses. For that court proceeding, his occupation was given as a ‘fitter’. The details of the offenses related to the fraudulent cashing of cheques in the names of J. Holmes, A. Holmes, and J. Jones, although in one offence he mistakenly signed it ‘G. Holmes’. The fact though, that he calls the design the ‘Wentworth Cruiser Tank’ and not the Heeney Cruiser tank is probably a good indicator that his real name was, in fact, Wentworth.


Mr Heeney or Wentworth, depending on which name he really was known by, was a criminal and clearly not a very good one. Between May 1925 and January 1940 he had amassed no less than 39 separate convictions which perhaps explains those 18 years of ‘tank study’ he mentioned in his opening letter. It is hard to know what to believe from the pen of Mr. Heeney therefore. A multiple times convicted criminal with a penchant for fraud and the use of multiple aliases. In his defence at court in 1940, he stated that “I have been in this sort of trouble since the War… when I am drunk I am not responsible for my actions”. Whilst he may have been drunk when he committed those crimes he did claim his wife had died in 1939, just three weeks before his conviction in January 1940 begging the question of just how she had spent £800 pounds on his tank by 1942. Heeney/Wentworth, a native of New Zealand, stated his intention to just go back home. Perhaps this was just an elaborate ruse by a hardened felon to con money from the government, or perhaps it was the last chance of a former soldier to serve his country with a genuine attempt to design and deliver a tank for the new war. Whatever the reason though, the design have been lost to time and the potential of his ideas was never realised. The fate of Mr. Heeney/Wentworth following his release in October 1942 is not known.


Australian Army Inventions Directorate file 775, 1942
The Evening News (Queensland) 3rd January 1940
Maitland Gaol

WW2 New Zealand Armor

Bob Semple Tractor Tank

New Zealand (1940-1942)
Tractor Tank – 3 Built

Few tanks have achieved the level of notoriety and even scorn which has been cast upon the ‘Bob Semple Tank’. Few lists of ‘Worst ever tanks’ miss it out and it does seem perhaps a little ungainly at first glance. As such it is ignored for what it really was and for the genuine merits it offered. The eccentricities of the vehicle and the character of the man whose name was applied to the vehicle have become legend.

Robert ‘Bob’ Semple (21 October 1873 – 31 January 1955)Robert ‘Bob’ Semple (21 October 1873 – 31 January 1955)

The character of the man

Robert Semple was certainly a ‘character’ and, in some ways, the vehicle even reflected him and his attitudes. He was born on 21st October 1873 at Crudine Creek, New South Wales. He started life on the rough goldfields of Australia before moving to New Zealand and at various times been a boxer in his own right as well as a miner, industrialist, union leader, and champion of the common working man. He had campaigned against involvement in World War I and was a talented orator and public character.
At one point, he had been prosecuted for refusing to disclose his son’s age to a defense officer and upon the introduction of conscription in New Zealand in 1916 had sought to use the vital position of miners to force the government to abandon compulsory service. In December that year, he was arrested again after advising miners not to be “lassoed by that Prussian octopus, conscription” and even denied a jury trial under the then newly introduced War Regulations Act. Upon his release in September 1917, Semple toured the coalfields and was very well received. After WW1, his political career waned until the Labour party returned to power in 1935 and he became a cabinet Minister for Public Works.
Robert Semple on a caterpillar tractor, between 1935-1940
Robert Semple on a caterpillar tractor, between 1935-1940 – NZ National Archives Photo Ref: 1/2-041944-G
This time, when war broke out, Semple was still fighting for the common people but was much less tolerant of dissent. In 1940, Robert ‘Bob’ Semple was given the portfolio for National Service; the de facto Minister for War, where, in a remarkable U-turn, he helped implement conscription. The idealist Semple had become the hardened fighter and pragmatist Semple. A man of strong convictions, virulently anti-authoritarianist and anti-communist, Semple was now an experienced political boxer. He needed to be too, as WW2 was a different beast to WW1.
In WW1, the ideal of sending troops to fight for the mother country was contrasted to WW2 where the prospect of a Japanese invasion of the islands of New Zealand was a very real and very frightening proposition. The Japanese had rolled through the forces of the French, British, and Dutch in the Far East and were openly talking about how undefended and vulnerable New Zealand was. New Zealand was virtually defenseless with just six Bren Gun Carriers in the whole country as its armored force. With Britain fighting for its own survival, supplies of War Materials, from rifles to tanks, were not going to happen for some time. If New Zealand was to defend itself it would have to do it itself. Semple himself remarked that:
“If this country is going to be invaded, we need to have equipment as good as that of the other fellow, if not better… we could not buy tanks from outside, but had to act on our own resources. Luckily we had big tractors here, and they were a godsend. They have proved one of the greatest boons the country has ever known, permitting us to build highways, aerodromes, camps, and fortifications in record time in the Dominion. They have proved invaluable for other urgent purposes outside New Zealand.”
Robert Semple (cane in hand), then Minister of Works, on a Caterpillar diesel bulldozer, 29th of March 1939
Robert Semple (cane in hand), then Minister of Works, on a Caterpillar diesel bulldozer, 29th March 1939 – NZ National Archives Photo Ref: 1/2-105128-F

A legend is born

New Zealand was facing a potential invasion with no effective armored force, Semple found out that the NZ Defence Department had been making enquiries in the USA for supplies of armor plate. However, Semple had already seen a photograph of a Caterpillar tractor which had been converted in the United States (it is possible that this refers to the Disston tank, however, no direct proof exists) and showed it to Mr. T.G.Beck (Public Works Engineer, Christchurch) who at the time was in charge of a large irrigation scheme in the South and Mid-Canterbury region.
It was going to take some time to obtain blueprints of the American tractor tank conversion but rather than squander time, work began straight away, without the formal plans under the direction of Mr. Beck in the Public Works Department (PWD) workshops in Temuka. Mr. Beck would work with an engineer at the PWD works, Mr. A.D. Todd, and all work was overseen by Mr. A. J. Smith in the capacity as an observer.
One of the PWD Caterpillar tractors working on a project at Lake Taupo, May 1941
One of the PWD Caterpillar tractors working on a project at Lake Taupo, May 1941 – Photo: Auckland Star
At Temuka, the PWD proposed to take their fleet of 81 D8 Caterpillar tractors and build armored bodies for them. The tractors could be used for their normal purpose and, if called upon for War Service, could have these armored bodies fitted. Very little modification was required of the tractors. The suspension was modified slightly and the track assembly was lengthened slightly. The existing driver’s controls were changed slightly and moved forwards. Mild steel extensions were added to which the body would be attached.
Prototype tank receiving a two-tone camouflage coat of paint - note the lack of the corrugated armor which is yet to be fitted
Prototype tank receiving a two-tone camouflage coat of paint – note the lack of the corrugated armor which is yet to be fitted – Photo: Classic Military Vehicle

The prototype

A prototype was ready at the Temuka PWD Depot by June 1940. The existing tractor body was removed and substituted by a 3 ply-plywood mockup of the armored cab attached to those mild steel extensions. Even at this early stage, the idea of a proper cannon for anti-tank use and infantry support was mooted. The original gearbox turned out to be insufficient and therefore an improved 2:1 ratio box was substituted. This resulted in the metal prototype having a shortened engine compartment and wider sides.
A 37 mm cannon in a revolving turret was seen as being of crucial importance, as was the provision of machine guns. It was sadly found to be impossible at the time to obtain a cannon so an additional machine gun was used instead. There are no details of what 37 mm may have been envisaged but the 40 mm 2 pounder gun which was the standard British tank gun at the time was in short supply. Having looked to the USA initially it would be likely that this 37mm gun considered was the 37mm M3 tank gun as used on the Stuart light tank.
The additional turret machine gun brought the armament to a total of six Bren .303 caliber machine guns; one on each side, one over the back, one in the turret, and two positioned forwards in the hull. One on the far right and a second one positioned centrally which would have been very awkward to operate given the position of the engine and would have to have been operated either awkwardly from the side by the driver or other gunner, or by another crew member lying on top of the cowling over the engine. The crew is often quoted as 8 based on these 6 machine gun positions, a commander and a driver but is also variously noted as 6 and as 7 crew. Clearly, the crewing would be dependent on the number of men available and the situation encountered.

Proposal of a 37mm gun turret.
This prototype was reordered in mild steel and the need was to construct an example for the Army in actual armor plate. Supplies were not available even from Australia so instead, corrugated manganese plate was used. Trials at Burnham Camp on December 1940 showed the speed had been reduced with this additional weight to only 8 to 10 km/h (5-6 mph). Additionally, the bulk of the body meant it rolled badly during off-road movement making firing on the move very difficult. The Army was still frustrated at the lack of a turret mounted cannon but with no other options available relented to have three examples constructed as they were.
Photograph of ‘Tank designed by Robert Semple between 1940 and 1941’
Photograph of ‘Tank designed by Robert Semple between 1940 and 1941’, NZ National Archives Photo Ref: 1/2-050790-F. Note the absence of all of the corrugated armor plating which was not yet fitted and the absence also of the additional armor plates over the machine guns, turret face and drivers hatch
Robert Semple (with cane) accompanied by unidentified staff officer inspecting the very tall sides of the PWD tank
Robert Semple (with cane) accompanied by unidentified staff officer inspecting the very tall sides of the PWD tank. Note this photo shows the back of the vehicle and clearly shows the corrugated armor on the right-hand side extending all the way up the side.

Into construction and the public eye

This construction was carried out in the Railway Workshops in Addington, Christchurch in January 1941 with the first one ready in under a month under the direction of Mr. Hoare. The armored structure of this tank consisted of 8mm thick (0.31 inch) armor plate, fully welded, on top of which was an addition of 12.7mm thick (0.5”) manganese rich corrugated steel plate. Popular myth has it that it used corrugated roofing metal and this is probably the origin of the myth that the vehicle was badly armored. This layering system was devised by Mr. Beck and was “severely tested”. The result was that this arrangement was felt to be sufficient to stop enemy anti-tank rifle bullets up to 20 mm (0.79 in) caliber as well as being easy to fabricate. Trailers were also devised for these vehicles so that they could be towed which, according to the October 1941 assessment by Major General Puttick,
“enables the machine to be moved very rapidly over long distances. Loading and off-loading is a matter of minutes only”
‘Semple’ tank loaded onto special transport trailer for rapid deployment
‘Semple’ tank loaded onto special transport trailer for rapid deployment – Photo: New Zealand Herald, 21st April 1941
By March 1941, the second tank was finished, and both took part in a parade in Christchurch on 26th April. One was then sent to Wellington and then on to Auckland to promote the war effort. It was paraded there on 10th May 1941. These public outings, as well-intentioned as they may have been to bolster flagging domestic spirit, instead promoted media ridicule. Only after these public outings did this tank become known as ‘Bob Semple’s Tank’.
Semple Tank being loaded/unloaded at a port as part of its journey to Auckland, May 1941
Semple Tank being loaded/unloaded at a port as part of its journey to Auckland, May 1941 – Photo: Auckland Star, 6th May 1941
Two ‘Bob Semple tanks on parade in Christchurch on the 26th of April 1941.
Two ‘Bob Semple tanks on parade in Christchurch on the 26th April 1941. The arch in the background is the Bridge of Remembrance – Photos: Christchurch Libraries and NZ Herald respectively

Bob Semple Tank
A Bob Semple tank in the livery suggested by contemporary photos.
Semple Tank on parade in Auckland, 10th of May 1941Semple Tank on parade in Auckland, 10th of May 1941Semple Tank on parade in Auckland, 10th of May 1941
Semple Tank on parade in Auckland, 10th May 1941 – Photos: NZ Herald
‘Is Mr. Semple in please?’ ‘Just a minute,-I’ll see!’
‘Is Mr. Semple in please?’ ‘Just a minute,-I’ll see!’ – Cartoon: New Zealand Herald, 13th May 1941

To the test

In August 1941, the vehicle’s armor was to be subjected to intensive machine gun fire and accurate close range sniping and in doing so highlighted some weakness in the design around the machine gun ports allowing for bullet splash to enter. Even so, in the absence of an alternative tank, General Puttick remarked that it was a very useful weapon for certain styles of fighting. It was powerfully armed and the speed was sufficient. The only unsatisfactory part was the height of the vehicle, in particular, the turret. The turret added more than two feet (>600 mm) to the overall height of the vehicle. Lacking a cannon in the turret, the additional machine gun provided little extra firepower to the other machine guns so General Puttick recommended the removal of the turret. Semple was to comment later that month on this creation that:
“The tank was not a stroke of genius on the part of the Minister of Railways, but an honest effort on the part of the military and the Public Works Department to create something out of the materials we had. It was made by the will and consent of the military”
‘25 ton tank constructed by the Public Works Department’
‘25 ton tank constructed by the Public Works Department’ – Photo: New Zealand Herald, 8th October 1941
Semple Tank undergoing trials
Semple Tank undergoing trials. Note the LMG – Light Machine Gun range in the background

Major General Edward PuttickMajor General Edward Puttick

Further tests of the ‘Semple tank’, as it was now commonly known, were carried out at Burnham camp by  8th October 1941 and witnessed by Major General Puttick (Chief of New Zealand General Staff). General Puttick was an experienced combat officer who had recently returned from the War in the Mediterranean. He noted that that at 25 tons (although the Semple tank did not weight this much) vehicles were still too heavy to cross bridges and would have to ford the streams instead but that overall:
“The arrangement of the turret and of the machine guns was ingenious and efficient” and that “I was impressed with the skill and ingenuity displayed by those concerned in the tank’s design and manufacture, adapting a civilian vehicle for military purposes”
It didn’t matter though if the vehicle had merit or not. It had become tied to Semple personally so his opponents politically could attack him by way of attacking ‘his’ tank and its unconventional appearance combined to doom it to being a laughing stock. This cartoon appeared on 21st October 1941 coinciding with the arrival of the first Valentine tanks in New Zealand.
‘Don’t look know but I think there’s something following us!’
‘Don’t look now but I think there’s something following us!’ Bob Semple appears in caricature with his head out of the turret which is unusual as there was no turret hatch on at least one if not all of the vehicles. A flaw which seems to have gone unnoticed by contemporary commentators – New Zealand Herald 21st October 1941 [Note: The turret of the vehicle is actually marked ‘Semple Mk.II’]
Semple Tank undergoing testing showing the roof of the turret.
Semple Tank undergoing testing showing the roof of the turret.
A view of the top of the ‘Semple Tank’ turret shows just a simple lifting eye and the absence of a turret roof hatch. Of all of the flaws mentioned of the Semple tank, this lack of a hatch is the most notable by its absence. This would have seriously hindered the observations from the vehicle as well as ensuring a fiery death for most of the crew. A single rear door being totally inadequate for even 6 men to exit in an emergency. Even with that flaw and its other shortcomings, Semple was rightly unrepentant saying in late October 1941:
“That tank was an honest-to-God effort to do something with the material at our disposal when raider were at our back door…instead of sitting down and moaning we felt we ought to do something to manufacture weapons that would help to defend our country and our people”
At some point, these two tanks were officially handed over to the Army, reportedly having had their turrets removed. Suitable cannons had still not been obtained. General Puttick’s final recommendation was that no more of this vehicle type be made and that the three existing vehicles were deemed to be suitable for beach defence instead. Eventually, the armored bodies were stripped back off the tractors and they were returned to their civilian duties. Time had gone by and the invasion threat was over. Better, faster indigenous designs were available, Valentine tanks were being delivered, and the Bren Carrier was in production locally to boot. The Semple tanks were simply not required anymore. The third vehicle, which had remained in Auckland, was reportedly deployed into service in the Pacific theater, albeit stripped down and fitted with a dozer blade.

Semple tank without turret

End game

Despite all of the scorn and mockery, Semple was still defiant and with plenty of justification. Under Robert Semple the almost defenseless islanders of New Zealand had developed their own armored force and demonstrated the resolve to fight and to resist. Semple, in a political exchange in September 1943, said:
When we came into office we had insufficient strength to protect a currant bun from the attack of a blowfly. But if the Japs could be killed with wheelbarrows we could have stoushed them – we had plenty of barrows…two years before the war we quietly slipped machines to Fiji and Tonga and built aerodromes there secretly… it was plain as the day that the Japs would strike south through the back door to Singapore… [island hopping] …to New Zealand..what stopped them this way?
A retort from the floor mocked Semple saying:
Probably your tanks, Bob
to which he responded
If that is a cheap sneer, you keep it. I had the vision to try and create something while a lot of others were just sniveling” [Laughter and applause to this response is recorded]
This was not the response of a man in any way ashamed or embarrassed but rather proud in what he and the PWD achieved.
Postwar commentators may also continue to sneer at this ungainly machine, but the PWD and Semple had laid down a marker, a line in the sand that New Zealand would defend itself no matter what. Semple, the fighter, the anti-authoritarian, would not give up the defence of his home to the dictatorship of Japan no matter what.

Major General Robert YoungMajor General Robert Young

The last word should go to Major-General R. Young (Dominion Commander of the Home Guard) who was touring with Bob Semple in November 1940 promoting home defence. General Young summed up the character of the man saying:
“I am proud to be associated with him. He has for what I wish everyone had – a will to win the war – for when a man has got a will to win, nothing can stop him”

‘Semple Tank’ / PWD Mobile Pill Box specifications

Dimensions 13’9’’ x 10’10’’ x 12’’ ft (4.2 m x 3.30 m x 3.65 m)
Total weight, battle ready ~18tons (including 2 tons of armor plate)
Crew 6 (commander, driver, 4 x machine gunners)
(additional crew could be carried up to 8 men total)
Propulsion 6 cylinder Caterpillar diesel, 95 kW (127 hp)
Also given as 108 hp (flywheel), 96 hp (drawbar)
Climb 1 in 2 grade
Fording 4 feet (1.22 m)
Embankment 4.5 feet (1.37 m)
Other notes Could crush saplings up to 6” diameter
Fitted with drawbar for towing of light field guns or an armored trailer
Armor 0.5″ (12.7 mm) Manganese Steel in V corrugated form backed by 0.31″ (8 mm) steel plate
Speed 7.5 mph normal, 1.5 mph (2:1 gearbox) (12 – 2.5 km/h)
Suspension RD8 Caterpiller (1939) modified and lengthened
Range 160 km (100 mi)
60 hours of operation
Fuel 90 litres of diesel held in two frontal fuel tanks
Armament 6 x .303 calibre Bren light machine guns with 25,000 rounds, (1 in turret, 1 rear, 1 left hand side, 1 right hand side, 2 forwards)
37 mm cannon (proposed but not fitted) with 5 machine guns
Total production 3


The Years Back: Making Do
New Zealand Munitions


New Zealand Newspapers

  • Evening Post, 16th November 1940
  • Evening Post, 31st March 1941
  • New Zealand Herald, 1st April 1941
  • New Zealand Herald, 21st April 1941
  • New Zealand Herald, 10th May 1941
  • Auckland Star, 10th May 1941
  • Auckland Star – Supplement, 10th May 1941
  • New Zealand Herald, 12th May 1941
  • New Zealand Herald, 29th August 1941
  • New Zealand Herald, 6th October 1941
  • New Zealand Herald, 8th October 1941
  • New Zealand Herald, 21st October 1941
  • Evening Post, 27th October 1941
  • Press, 28th October 1941
  • New Zealand Herald, 29th October 1941
  • Evening Post, 23rd September 1943
  • National Library of New Zealand
  • Len Richardson. ‘Semple, Robert’, from the Dictionary of New Zealand Biography.
  • Te Ara – the Encyclopedia of New Zealand,  (accessed 27 December 2016)
  • The Semple Tank, J.Plowman, Classic Military Vehicle Magazine