Experimental WWI Tanks - Part II

While the first instalment looked at early experimental tanks, this blog post examines vehicles created as a reaction to problems tanks were encountering in combat, such as the Invicta Roller and tadpole tail. 


Perhaps not really an experimental tank, but definitely a one off, was this machine seen at Bovington towards the end of the war.

It is a Mark IV, unusual enough since it’s a supply tank sporting a training number, but what sets it apart is the lifting apparatus. There is a jib at the front such as is normally attached to salvage tanks, but the winch mounted at the back is the real oddity. It is manually operated hence the platforms on either side.

The impressive salvage tank used at Bovington Workshops during the First World War. It must have had quite strong lifting powers.

It is worked by two men, winding handles, with a line leading to the jib at the front. Normally tanks with the jib fitted rely on a chain hoist, worked from the ground, but this is something altogether more substantial.


The airship handling tank at Pulham about to start towing the rigid airship Vickers R23.

The Royal Naval Air Service airship station at Pulham in Norfolk acquired a Mark IV female that they fitted out with a tower-like device that was used to haul airships in kindly weather, instead of a ground handling party. It appears to have worked quite well although communication with the crew must have been difficult. In this picture men are being used to hold the airship down, with the tank standing by to tow it. The authorities at Pulham requested a Mark V to replace the Mark IV, but the War Office turned this request down.

Roller Chain

Renolds roller chain, marketed by the Anglo-Swiss Hans Renold, was made in Manchester and used quite extensively in British tanks during the First World War. However this version was unique, two loops of chain passed clear around the tank, driven by toothed sprockets at the back.

The plan was to use the moving chain to carry the unditching beam around, independently of the tracks, so that nobody had to climb outside to attach it.

The Mark IV male tank fitted with Renolds chain unditching gear, seen on the original Tank Museum at Bovington shortly after the First World War. Note the rollers that carry the chains around the tank until they vanish underneath.

Quite how it worked underneath the tank we don’t know, or whether it was really strong enough for the work. The prototype was only ever photographed at Bovington and may have been invented there, but it was never used in action and probably never left England.

Mines and Tadpoles

Invicta mine rollers attached to a Mark IV tank, the rollers castored when the tank was steering but they did not survive the detonation of a mine. Trials were carried out at Claremont, now a National Trust property at Esher in Surrey.

When he was removed from the Dover Patrol, Admiral Sir Reginald Bacon joined the embryo Tank Board. He was charged with devising a means to clear mines, which were proving to be the curse of the tanks. One of his first efforts was the so-called Invicta Roller, which used the front rolls from two steam rollers fitted to the ends of two long wooden beams attached to the front of the tank.  It does not appear to have been a great success.

The Germans built stronger defences with wider trenches to hinder the tanks, the British response was to make longer tanks.

One answer, devised by William Foster & Co. of Lincoln was the Tadpole Tail added to the rear of a Mark IV, making the tank about six feet longer. It could also be fitted to a Mark V tank, but although many tails were made they don’t appear to have been used on active service, the complaint being that they were not rigid enough. However some were tested in Britain and some were sent to France but never used.

Later a Tadpole Tail machine was tested at Dollis Hill, the experimental tank establishment in London. One of the experiments involved a six inch mortar, mounted between the rear horns and designed to fire over the tank into enemy trenches. Quite where the crew would stand isn’t entirely clear, but again since the equipment was never used in this way it is only academic.

A Tadpole Tail attachment being tested in Lincoln over a wider trench. It was an ingenious idea but one that did not work under battle conditions.

The location of the mortar provides some protection for the crew although the shock of firing the weapon must have weakened the frame it was standing on.

Enjoyed finding out about these weird and wonderful creators? Find the first instalment here and the third part here

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