Experimental, United Kingdom, WWII

Praying Mantis – A Machine Designed to Fire Over Obstacles

This is the Praying Mantis, an extremely bizarre piece of British engineering that stands out as one of the most unique tracked vehicles ever made.

This WWII-era machine took an entirely new approach to armored fighting vehicle design, with a pivoting crew compartment that could be raised up to fire over obstacles.

When lowered the vehicle had a waist-high silhouette and could move undetected behind low obstructions, including tall grass.

It was built on the chassis of the sturdy and reliable Universal Carrier. Unlike that workhorse though, the Praying Mantis was a little too “weird” for use, and was not adopted.


A Strange Idea

The basic premise behind the Praying Mantis was a vehicle that could position itself behind an obstacle, raise a weapon system over the obstacle and fire.

This method would have presented a very small target to the enemy, while using the obstacle to augment its camouflage and armor protection.

Ernest James Tapp, the co-founder of County Commercial Cars created and privately funded the Praying Mantis.

His initial designs were based on a custom tracked chassis, one which was used for his first prototype.

The first Praying Mantis design.
The first Praying Mantis design being offloaded.

He patented the design in 1937 and started actually building them in the 1940s.

This unorthodox design required the crew to lie face down inside the “raising” section. The first prototype was created to test the feasibility of such a system, which forced the crew into a rather unnatural position to control it.

In 1943 a more sturdy prototype was built, this time on the chassis of the Universal Carrier – the most produced armored fighting vehicle in history.

A Universal Carrier or Bren Gun Carrier.
The rather simplistic Universal Carrier certainly lived up to its name, being used in huge numbers thanks to its excellent versatility. Image by D. Miller CC BY 2.0.

Its massive production run of over 110,000 is a testament to the Universal Carrier’s usefulness during wartime. It had thin armor but was extremely versatile, serving as an artillery tractor, troop transport, cargo vehicle and reconnaissance vehicle, just to name a few.

The Universal Carrier’s most interesting feature was its method of steering. This was achieved by literally bending the tracks by a small amount, steering it in a similar way to a wheeled vehicle.

The tracks would brake in a more conventional way during tighter turns. It was propelled along by a 3.9 (239 cubic inch) liter Ford V8, which produced 85 horsepower.

Universal Carrier running gear.
The Universal Carrier was steered by bending its tracks. This was achieved via a crosstube that moved the bogies side to side.

Praying Mantis

Being produced on this chassis, the Praying Mantis continued to use the same drivetrain and running gear, but the upper surfaces were significantly modified to accommodate the elevating crew compartment.

It only had a crew of two, who were both situated on their stomachs in a face-down position inside the crew compartment. This was basically a long hollow box known as the “control chamber”.

The Praying Mantis.
The Praying Mantis with its fighting compartment raised. Image by Leander9999 CC BY-SA 4.0.

On top of this was another section that pivoted up and down independently of the control chamber to finely adjust the guns’ elevation. This was known as the “head”.

Finally, on top of the head was a small box that housed two .303 Bren light machine guns – the only offensive armament on the vehicle.

This component – known as the “helmet” – controlled the guns’ side-to-side movement.

Praying Mantis "head" and folded fighting compartment.
The “helmet”, seen on the right side of this image, contained the Praying Mantis’ armament. Image by Makizox CC BY-SA 4.0.

These three sections could be elevated as one, from completely flat against the Praying Mantis’ hull to a 55 degree angle.

In this position, the guns were 3.5 meters (11.5 ft) high, enough to clear most and walls and hedgerows.

A hydraulic system at the bottom of the assembly controlled its movement. Interestingly, the Praying Mantis could be driven with its crew compartment in any position.

In actual use, the Praying Mantis would drive along with its crew compartment slightly elevated. It would then approach an obstacle, raise its head and begin firing at an enemy.

Praying Mantis diagram.
A general depiction of the crew’s position within the Praying Mantis.

From the enemy’s perspective, the vehicle presented an incredibly small target to hit, one that was not much larger than a man’s head.

Once firing was complete, it would simply drive away. During the entire process the crew would have been protected and out of sight.

When fully depressed, the machine was extraordinarily low, enabling it to make a quiet getaway behind fences or even long grass. Driving at maximum elevation was probably quite unsettling for the crew.

During tests this is pretty much what happened.


The machine underwent trials and was found to technically achieve its purpose of firing over obstacles, but to do so it made too many compromises.

It was hard to control, hard to aim and offered very little armored protection should it get caught in the open. In addition, the machine would bounce so much that it made the crews sick.

Praying Mantis with its fighting compartment slightly raised.
When raised, the top of the Praying Mantis was over 3 meters high, allowing it to peek over obstructions. Image by Hohum CC BY 3.0

The Praying Mantis project was scrapped in 1944, and has since become somewhat of a meme in the tank enthusiast community for its sheer “uniqueness”.

Unfortunately the first Praying Mantis prototype was scrapped, but the second Universal Carrier-based one survived, and is on display at The Tank Museum, Bovington today.

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Amazingly, its pivoting mechanism still works.