Crompton was also becoming concerned at the lack of communication with the military and the continuing vagueness of his design brief. He needed specifications for armour and armament, and as he made clear in a progress report of 9 April, he could not get far without more information on proposed tactics. Churchill’s near obsession with a monster machine had been scaled back to reality by d’Eyncourt who had set a 25–30-ton design limit. The committee was, however, left with the First Lord’s tactics as originally interpreted by Dumble and Crompton, and implicitly accepted thereafter by Churchill and the others. They were trying to pack a substantial assault party and light support weapons into an overlarge machine to be run right up to the enemy trench; the alternative was Sueter’s less technically challenging gunship, heavily armed but lightly manned to provide close fire support for attacking infantry. The committee was pursuing the motorized equivalent of a medieval siege tower.
Hetherington and Stern accompanied Crompton on a visit to the front on 21 April, intent on seeing captured German trenches at Neuve-Chapelle. Crompton put up his Crimea medal for the occasion. They reached Boulogne at noon and motored on to the RNAS base at Dunkirk where they were met by the Duke of Westminster, who had taken over the Villa Mugusta on the Plage. Unfortunately the trenches had been recaptured and there was little to see from an observation tower. Next morning they drove to GHQ at St Omer, stopping en route to measure canal bridges and road curves. On arrival the Admiralty party was told that no information could be given to them without clearance from the War Office and they could not enter the battle zone. Hetherington recalled that the Staff dismissed the landships idea as a joke and a waste of public money. The trio was ordered home. They had planned a six-day inspection; instead they were back in London 38 hours after setting out. They had been within feet of the office of the one man who could give them the information and encouragement they needed, but Swinton was unaware of their mission.
However, it was clear enough to Crompton from his observations that the crawler’s 80ft steering radius would have to be halved to get it up to the front. He began work next morning, a Friday, and the routine committee meeting was postponed to noon Saturday. The colonel abandoned the rigid Mk I Pedrail in favour of an articulated machine – a scheme Tritton had already decided upon. The difference between them was Crompton’s preference for independent power to both platforms of his turretless 34-ton set. Fifty-six men would be carried in the side aisles and eight more on platforms fore and aft. The 8mm armour plate was increased to 12mm to resist reversed bullets. To help offset the extra weight the panel height was reduced to 4ft 6in, compelling the troops to be seated and further lowering the hull profile. Tactics were also altered. Enemy trench lines were interrupted by frequent traverses which would prevent the landship’s machine guns from raking long sections in enfilade fire. Instead of driving head-on over no-man’s-land before mounting the parapet and overhanging the trench, they would cross in a zigzag approach and halt broadside to the trench to deliver preliminary fire with grenade throwers. These should disable long stretches of trench prior to releasing the storming party. Later, Crompton further refined these tactics to provide a rolling barrage of mortar fire from the machines, moving slowly parallel to the trench and 100yd back from it. The armoured side panels were top-hinged for quicker exit. When they were swung open, hinged base plates fell to form a skirt around the machine, giving added protection for any wireclearing party working on the ship’s lee side. Loopholes for rifles and machine guns encircled the hull. The committee approved Crompton’s proposals for his Mk II ‘B’ Type Pedrail. He had completed the basic design with his three draughtsmen in 24 hours.
A lightweight US chain tractor arrived at the Wormwood Scrubs depot in late April. It proved to be a lucky break. The iron windfall came from the Killen Strait Mfg Co. of Appleton, Wisconsin, whose London agent had written to the director of Admiralty contracts advising that a machine had arrived and that William Strait was in town and would be glad to give a demonstration. Dale Bussell saw the letter and alerted Crompton. After booking a viewing the colonel searched the country for other American crawlers, while continuing to give Holt’s machines a wide berth.
Strait brought his tractor to the Clement-Talbot works on 27 April. With a tricycle layout like the much heavier Holt, the machine took its drive through a short rear-mounted pair of caterpillars, but in place of a wheel up front it was fitted with a small steerable track. The little Strait was well designed and engineered. It greatly impressed Crompton, although Hetherington’s mud pit was too much for it and an armoured car had to haul the machine out. All three track girder frames pivoted at one end with a shock-absorbing spring at the other to reduce the jarring of unsprung machines. Interestingly, the rear face of the driven tracks was angled upwards and rearwards to help the tractor climb obstacles in reverse gear. This neat and novel arrangement of Strait’s was reflected in the angled front profile of the first tank, which almost certainly had its origins in his Wormwood Scrubs demonstrator.
Crompton arranged the purchase of the machine for £800. He had a platform fitted and test-laden to see what the axles could stand. Strait’s London agent, H.H. Chipman, had actually contacted Crompton early in January to extol the virtues of the tractor, though it seems no machine had been shipped over.19 Crompton was still a convinced wheels man then, and did not respond. His new interest in American crawlers coincided with doubts concerning Diplock. Chipman’s invitation and Bussell’s prompting were indeed timely. The next day, 28 April, in the heavy rain which seemed to dog tractor trials that year, Crompton, Legros, Hetherington, Stern and Wilson drove to marshes in the Thames estuary. A US Bullock tractor was put through its paces close by J.B. White’s cement works at Swanscombe. The 8-ton machine, a semi-track crawler steered through two front wheels, was considered to be quite advanced. It successfully hauled 5 tons of stone though the wagon was sunk to its axles. In a follow-up letter to John Palmer junior, Bullock’s London agent, Crompton was sufficiently carried away to reveal the purpose of the exercise:
I am about to put a proposition before my Committee that I be allowed to order from you two of your Californian Creeping Grip Tractors for the purpose of providing them with an armoured platform … for carrying … thirty men across a fire-swept zone near the trenches… Our eventual object, however, would be to purchase from you portions of your Creeping Grip chassis enlarged from any of your existing patterns as shown on the enclosed drawing. The enlargement is in the direction of length and is mainly for the object of allowing the tractor to traverse wider ditches or depressions than is possible with your present type … I have been preparing designs of two such chassis which are to be coupled together by substantial coupling, in such a manner that they will provide an almost continuous platform for sixty or seventy men… We are also providing arrangements to make a joint between the two chassis sufficiently rigid to make the two frames into one continuous girder for crossing shell holes or depressions up to 10ft in length.20
Following the icy reception at GHQ, Crompton again raised the matter of the information vacuum in which the committee was working. He addressed a long memorandum to d’Eyncourt on 29 April detailing the progress of design and tactics as evolved by his team, and his pressing need for confirmation that they were on the right path. He lacked the most basic information, including the nature and defences of enemy trenches, the preferred tactics and radius of action of the machines, how they should be armed and what means of throwing bombs, and whether night attacks were planned. Crompton requested a conference with engineer officers at St Omer. Knowing the War Office would only delay matters, he also wrote direct to Gen Sir Horace Smith-Dorrien who was commanding the reorganized 2nd Army in France. The letter went by courier next day:
I, the old Colonel of the Electrical Engineers, am now employed by the Admiralty to prepare designs for … trench attacking devices … twelve of one kind and six of the other have been ordered, and are now well in hand… As you know me sufficien
tly well you could help me if you asked Sir John French to allow me to come to you to confer with yourself, your CRE or other officers best fitted to help me with advice. I can be at Dunkirk within 24 hours of receiving a telegram.21
Crompton showed d’Eyncourt the letter a few hours after its despatch. He had again revealed the Admiralty’s hand to GHQ, never quite having grasped that Churchill had no intention of passing any landships to the army. D’Eyncourt told the colonel that Churchill had read his memorandum and had declared that it was up to the naval people themselves to secure the information. He emphasized to Crompton that he only approved the letter as a private communication, adding ‘… how are our landships to be used if not by the Naval Brigade?’22 This should not have come as a surprise. Murray Sueter had addressed written instructions on procedures to Crompton and Hetherington a month earlier, making clear that three new squadrons were to be formed to operate landships as part of Boothby’s armoured car force.23 Crompton’s abortive tour had not been cleared in advance with the War Office because Churchill presumably hoped he could bluff his way to the front without revealing his mission.
Smith-Dorrien’s reply on 3 May made clear that he could do nothing. Three days later the general was on his way home, having resigned his command after objecting to senseless losses arising from French’s orders during the second battle of Ypres. The C-in-C’s acceptance was conveyed to Smith-Dorrien by Gen William Robertson, French’s Chief of Staff, ‘’Orace – you’re for ‘ome.’
Crompton’s diary records that he ‘made a clean breast of my fears respecting Diplock’ at the landships meeting on 7 May. He was losing confidence in Pedrail’s ability to service the contractors, and the crawler demonstrations had undoubtedly been an eye-opener. Compared with the complexities of the Pedrail system, remarkable as its performance was, the American tracklayers were mechanically simple, robust, and in production. US plants had the resources to design quickly and build scaled-up track assemblies.
The committee decided to limit construction of tracklayers to two coupled sets for evaluation – a Mk II Pedrail type and a Mk IIA on Bullock tracks. Two Creeping Grip machines and spares were ordered. Bullock’s was also asked to lengthen two pairs of tracks and frames from the current 5ft to 9ft 8in centres, for which they promised delivery four months from receipt of drawings. Crompton’s one-time chief technical assistant, 32-year-old George Field, was to go out to Chicago to give design support and supervise the track work. He was also to assess the capacity of Bullock’s and others to build complete landships. Field was a very competent engineer, an automobile specialist with his own small factory. He had designed a light car, and co-designed with Crompton his 1908 steam gun tractor. The two men had produced the British Standard Fine screw thread.
The Bullocks were to be coupled on arrival in England before undergoing trials as a single articulated unit. Crompton had to devise a linkage and spent much time with Wilson grappling with the loads imposed on it by his two 14-ton chassis, both 22ft long, when each was driven through acute angles relative to the other. The coupling would additionally have to lock the two half-ships into a rigid girder-like whole when crossing trenches to prevent the lead unit from dropping its nose and ramming the far side. On top of these extremely demanding functions, it must transmit lift from the rear half-ship to raise the front end of the leading chassis several feet before attempting to cross wide shell holes or mount a parapet.
Though unimpressed with the twinning format, Wilson produced a design and model for a coupling on 25 May. Crompton accepted it and asked him to supervise the preparation and trials of the machines. The Bullocks would be coupled back to back, the rear of each having been fitted with a heavy 6ft high space frame. Between the two frames a very stiff universal coupling was set low down, on either side of which were powerful hydraulic rams to aid steering. It was more brute force than science. The steering technique entailed throttling back the lead half while accelerating the rear after setting the lengths of the twin rams appropriately. These would nudge the front half in the required direction, the universal joint acting as a fulcrum. The turn would be followed through with further applications of throttle and ram settings from the rear unit. The technique would all become very theoretical when the respective chassis were lurching over broken ground, each in a constantly changing plane relative to the other.
The locking together of the two ships as a rigid whole was to be achieved by a pair of winch-controlled cables carried over the top of the space frame and shackled well forward on the other chassis, which had a corresponding assembly. Either half-ship could bodily haul the front end of the other to hold it straight and level, or raise it up to 3ft off the ground preparatory to climbing a low trench parapet. The rear half would then drive forward on full power, ramming the raised lead unit up the mound. A plough fitted to the front half would push the remaining soil or sandbags off the crown of the parapet on this thrust. Other considerations apart, the exposed tackle was vulnerable to battle damage which could cripple the set, effectively breaking its back, but Crompton explained why he favoured coupled units:
A long series of calculations made by Legros and myself on our drawings of the jointed ships, have confirmed my opinion that the jointed principle by which one half of the ship forms the support to enable the other to be partly lifted over an obstacle or gap, is a sound one for these large compound vehicles. Moreover as the two halves of the vehicle are symmetrical the two coupled together form a double-ender train, which can be run equally fast or manoeuvred equally well in both directions, and thus obtain the great advantage of advancing or retiring out of the danger zone without the delay of turning round.24
Meanwhile at Lincoln a full-size wooden mock-up of Tritton’s articulated big-wheeler had been erected in a corner of Foster’s works. The outlines of the 15ft wheels were chalked on to timber framing. To reduce fighting weight to 36 tons the overall length of the March design had been cut from 48ft to 37ft by shortening the trailer which was now identical in size to the tractor. Each hull sat almost entirely within the circumference of its two wheels. They had also become double-deckers but the claimed capacity of 70 men was still highly optimistic. Tritton’s linkage operated broadly as Wilson’s, with two winched chains above a universal coupling, but without space frames the stresses were even greater.
The mock-up was inspected by Hetherington and Wilson on 16 May. It was obvious that the design was profoundly flawed. Soon afterwards Tritton went down to the Barlby Road depot for a review meeting chaired by Hetherington who told him the machine was likely to be a serious obstacle to military traffic near the front, particularly if knocked over by shellfire. Worse, the foreshortened trailer’s flanks were now wholly screened by its wheels and as a result the only free field of fire was a narrow arc rearwards, necessitating a battlefield ‘U’ turn to bring the armament to bear. The meeting, attended by Crompton, Legros, Wilson, Stern and Lt Symes, their armour specialist, considered placing the tractor behind the trailer to secure forward fire. This idea was rejected because the tractor unit had no steering, which also meant the set could not be reversed.
Tritton suggested that to improve its offensive capability he could decouple the machine and let the trailer unit operate as an independent fighting module, cable-linked to an electric power source on the remote tractor. This would entail a complete redesign but the RNAS team was enthusiastic. They saw possibilities for silent night approaches and increased payloads. Unmanned machines could be packed with explosive and, with locked steering, despatched at enemy positions before being detonated electronically. There appears to have been a collective retreat from reality that day. It is hard to believe that those present could have contemplated such a scheme had they been allowed to see the battlefields.
The committee asked Tritton to put his proposals in writing. His letter of 5 June to Crompton explained that he was abandoning both the twin-chassis format and ‘big wheels’ traction in favour of an ‘armoured wagon or fort’ on 8ft wheels.25 He
offered two types, both using the Daimler 105hp unit, either as a standard petrol-engined machine of just over 14 tons with complete freedom of movement, or a petrol electric ship linked by a mile of cable to a tractor-mounted dynamo. The cable drum could be carried inside the machine or on an armoured trailer. Tritton recommended the latter with an integral drum, its weight of nearly 18 tons dropping to less than 15 tons by the time the cable was paid out. The petrol version would allow 56sq ft of floor space for armament, ammunition, crew and stores, as against 82sq ft for the petrol electric. Tritton acknowledged the risk to crew and ship if the cable was shot away and was planning to plough it 12in deep as it was laid. The fact was, however, that he had reverted to the howitzer tractor chassis as the basis of design. Foster’s were effectively back where they had started three months before.
The Landships Committee was unimpressed, cancelling Foster’s order and closing down all work on wheeled ships on 8 June. Ironically, the very next day Tritton found himself at the Shoebury ranges with the cancellation fresh on his mind as he watched his Portable Bridge Machine fail its much-delayed trials. He claimed in 1918 that he had received an order, later cancelled, to build 70 trench-crossing fighting machines to a design drawn up on 3 June 1915. He even gave the drawing number, 101V.26 The Bovington Tank Museum has a copy which confirms this as the Portable Bridge Machine with a box-like armoured hull fitted with one forward-firing machine gun. The author has found no hint of any such order, actual or contemplated, in Admiralty or War Office files. Tritton only secured Churchill’s February order for 30 machines which was, of course, cancelled by him days later.
Crompton wrote a friendly private letter to forewarn Tritton of the committee’s decision and to assure him that it would do its utmost to put other experimental work his way. They were now left with the Pedrail and Bullock systems, and the colonel was seriously concerned about the lack of contact with army professionals who could give direction to the project and remove much blind guesswork. He was also questioning the pursuit of troop carriers to the exclusion of gunships. He had tried to meet Maj Gen Sir Percy Girouard, a member of the WO Munitions Committee and late Director of Railways to the South African Field Force, with whom he had served, but Girouard broke the appointment. Next day, 20 May, Crompton had unburdened himself to d’Eyncourt in a carefully prepared letter:
The Devil's Chariots Page 12