Britain’s Shellproof Tank:
 Part 1 - From Flotilla Leader to Battletank
by Roger Todd

Most major tank building nations have been seduced by the superheavy tank concept. A few monstrosities from the Second World War, such as the Germans’ 188-ton Maus, are well known, but it is not so widely appreciated that scarcely had the first experimental tanks undergone trials during the Great War than plans were set in motion to build 100-ton-plus behemoths. Appearing in most accounts as little more than a footnote was a British attempt to build a shellproof tank, known to posterity as the Flying Elephant. The first serious (as opposed to purely paper) project for a hundred-ton tank, the Flying Elephant was no mere whimsy or exercise in gigantism for its own sake, and nor was it a proposal merely to build a handful of monster machines, as appeared to be the case with the bloated German K-Wagen (an early manifestation of the notorious German obsession with size). The Flying Elephant was to represent a new class of tank, and the vehicle’s role developed beyond the initially somewhat vague, but understandable, desire for a shellproof tank for its own sake into something rather more interesting.

The design of the Flying Elephant was a protracted affair, and went through a number of radically different forms, as well as names, before finally settling down. In fact, the design process appears to have involved two distinct phases, and to make the story more digestible, it has been split into two linked articles:

Britain’s Shellproof Tank: Part 1 - From Flotilla Leader to Battletank

Britain’s Shellproof Tank: Part 2 – Birth & Death of the Flying Elephant

These articles will explore the complex design process, and the quite remarkable series of designs developed, as well as attempt to explain why the project ultimately failed.

Genesis

Development of the Shellproof Tank, or as it finally came to be known, the Flying Elephant, ran almost parallel with the creation of the first tank itself. The story has been told elsewhere of how, protected at a crucial early stage from the depredations of sceptics by the mercurial Winston Churchill, then First Lord of the Admiralty, the Landships Committee, formed in February 1915, had produced the first vaguely practicable cross-country armoured vehicle, Little Willie. But Willie was unsuitable as a fighting machine, and before long William Tritton, the brilliant engineer-director of William Foster & Co of Lincoln, and Lt Walter Wilson, an automobile- (and sometime aero-) engineer par excellence, had produced the classic rhomboidal Great War tank, Mother, matronly progenitor of the Mark I and its ilk, and far more suited to the task of churning across the Flanders mud.

But the early tanks were armoured only against machine gun and rifle fire, not artillery. With armour plating scarcely a half-inch thick, when hit by enemy shells they ran the risk of becoming instant crematoria for their unfortunate crews. Barely had Little Willie run his first trials in December 1915, then, than thoughts turned to heavier protection. Around Christmas 1915, the imaginative Col Ernest Swinton, in his new capacity as Assistant Secretary to the Committee of Imperial Defence (CID), noted concerns about the danger to the tanks under development from new German tactics using protected quick-firing (Q.F.) guns in a report copied to the Landships Committee. He recommended research into the capacity of light armour to resist small high-explosive (H.E.) shells, noting that Admiral Sir Percy Scott, the great naval gunnery innovator, had performed promising experiments a few years previously at Portsmouth into the effects of H.E. against submarine hulls.

This report did not in itself recommend, or even explicitly presage, the development of a special shellproof tank. It is clear that, at this stage, there was interest in determining whether it would be feasible to make the existing design of tank (Mother) resistant to shells, whether through a thicker single layer or a double-skin of the planned, relatively thin, bullet-proof armour. But the implications of the report were clear enough, however, and were to bear fruit within two months. On 14 February 1916, Swinton addressed a CID report entitled simply ‘TANKS’ to the General Staff at the War Office. After briefly discussing progress with the current design, Swinton wrote, ‘As you know, the machine approved and now being produced, is furnished with bullet-proof protection alone. The Tank Supply Committee, however, propose to try and evolve another and superior type of machine… which will be armoured so as to be proof against the high explosive shell from German field guns, and… the small calibre quick-firing artillery which it is believed the enemy may bring against them.’

A great deal of thought had gone into this proposal (indeed, the bulk of the report is devoted to it), as Swinton further requested the General Staff make their recommendations in respect of armour, armament, speed and climbing abilities, with their reply to be made direct to Albert Stern, the dynamic secretary of the Tank Supply Committee (successor to the Landships Committee). To put this into perspective, it must be recalled that the tank concept was still in its infancy; Mother had gone through her paces for the first time barely three weeks before, and it would not be until autumn 1916 that the first Mark Is went into action. The response was swift. Gen Bird, Director of Staff Studies at the War Office, addressed the Staff’s requirements to Stern on 19 February, noting that the new machine should: resist field gun fire; have no increase over the present armament of two 6-pdrs; have a top speed of 6mph (somewhat faster than Mother); and should be able to cross a ditch 10–12ft wide with a 6ft parapet and a trench 4ft 6in wide on the other side. Furthermore, it should not be very much larger, especially in height, than the current machine. If satisfying the speed and climbing requirements were to mean excessive size increases, then speed could be sacrificed.

The Tank Supply Committee now had detailed, if rather ambitious, specifications, and the next few months saw experimental work being carried out, mainly on armour plate. The Committee’s resident expert on armour was Lt Kenneth Symes, who had conducted experiments the year before into protection against bullets. From April until June 1916, he and Wilson organised a number of trials with plate supplied by Messrs. Beardmore & Co, the Glasgow shipbuilders. Indeed, the first experiments appear to have involved a German 77mm field gun which was sent to Glasgow for trials against 2in high tensile plate some time around 10 April. In June, Wilson reported that British 13-pdr and 18-pdr guns firing shot and shell were being used to test more 2-in plate. The results were promising enough that a Beardmore manager, Mr Service, stated that 1in and 1½in plate would likely be as effective as 2in, and recommended further tests.

The Flotilla Leader

The first design study would appear to have been the curious sketch made on 12 April 1916 labelled ‘Suggested Flotilla Leader’. This was for a 45-ton machine, with armour up to 2in thick, low-slung tracks like those of Little Willie, and a pair of sponson-mounted 6-pdrs at the front, near the nose. Between them, in a polygonal cupola, are five machine guns, with another six at the rear and two on the flanks. Under the cupola is what appears be a supplementary track higher than, and between, the main track units. This feature reflects Walter Wilson’s suggestion at the Tank Supply Committee meeting of 6 March that ‘the track should be made in two parts, the front track being double armoured’, to assist with climbing. Authorship of the design is unknown, though the handwriting on the sketch appears to be that of Wilson.

Foster’s Battletank

Whoever devised the Flotilla Leader, William Tritton’s first detailed design of 13 July 1916, called the ‘Foster’s Battletank’, bore a striking resemblance to the earlier sketch. At the front, under the armoured machine-gun cupola, hangs a full-width 2in armour-plate on hinges, which protects the front of the tracks. In all places at the front, the armour is 2in thick, with a double-skin of ½in armour protecting the sides. With the rear machine guns of the Flotilla Leader absent, the Battletank’s armament is concentrated forward, giving it a distinctly aggressive air. Trailing the rear is a larger version of the steering tail wheels of Mother and the Mark I tanks. No indication is given on the schematic design drawing of how the tail was to be attached to the hull, and the accompanying drawings reflect this vagueness. The machine is huge, 32ft 6in long without the tail wheels, 43ft with them. It was estimated that the machine would have weighed around a hundred tons. Two six-cylinder 105-hp Daimler engines were to be coupled together to produce 210-hp. Some accounts state that the engines were to have shared a common crankshaft, effectively making it a V12. But in all drawings of the various designs, the engines are always shown side-by-side, each with its own gearbox. Unlike the later Whippet medium tank, however, the engines did not power the tracks independently of each other. The gearboxes were coupled together and ran a single shaft. The new double-engine was ordered on 19 June.

At the rear is a short, pivoted pair of supplementary tracks, the first appearance of Tritton’s auxiliary track system, which he patented in late 1916. Unlike the well known final design’s tracks, which were to deal with ‘bellying’, or sinking in mud, these short tracks were to help push the machine over obstacles, or up the edges of craters, as can be seen in the patent sketches below. Why Tritton should have eschewed the front mounted track of the Flotilla Leader is unknown. Although they worked closely as a team on Little Willie and Mother, there was always an element of good natured rivalry between Tritton and Wilson, and if Wilson was indeed responsible for the Flotilla Leader sketch, this may have been Tritton’s way of placing his own inventive stamp on the new design.

This design was to change considerably, and until it was finalised, construction work could not begin, the only apparent progress during the ensuing months having been on the Daimler double-engine, as well as the armour plate experiments. The next design was radically different, and is dealt with in

Part 2 - Birth & Death of the Flying Elephant 

Acknowledgements

Gratitude is extended, in no particular order, to the following:
1        King’s College London, Liddell Hart Centre for Military Archives: Albert Stern Papers
2        David Fletcher, the Tank Museum, Bovington
3        UK Patent Office: William Ashbee Tritton, Pat. Nos. 126,070 and 126,076
4        John Glanfield: The Devil’s Chariots
5        Albert Stern: Tanks, 1914-1918: The Log-Book of a Pioneer
6        M J Verrall: 1995, unpublished monograph, the Tank Museum, Bovington