Mark IX tank

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Mark IX
The Mark IX tank (armoured personnel carrier)
Mark IX
Production history
Designer Lt. G.R. Rackham
Manufacturer Marshall, Sons & Co.
Number built 34 (total)
Weight 27 t
Length 9.7 m (31 ft 11 in)
Width 2.5 m (8 ft 1 in)
Height 2.64 m (8 ft 8 in)
Crew 4: commander, driver, mechanic, machine gunner; up to 30 men could be carried.

Armour 10 mm
2 x 0.303 in machine guns
none, but loopholes for 16 soldiers
Engine Ricardo 6-cyl petrol
150 horsepower (110 kW)
Power/weight 5.6 horsepower per tonne (4.2 kW/t)
Suspension unsprung
20 miles (32 km)
Speed 6.9 km/h (4.3 mph)

A British armoured fighting vehicle from the First World War, the Mark IX was the world's first specialised armoured personnel carrier (APC).


During the first actions with tanks, it became clear that infantry often could not keep up with the tanks; not because soldiers were too slow — the early tanks themselves could only move at a walking pace — but because soldiers on foot remained vulnerable to enemy machine gun fire, though tanks had been invented to solve that very problem. On many occasions, positions gained at great cost were immediately lost again for lack of infantry to consolidate. It was thought this problem might be solved by cramming a few infantry soldiers into each tank. But it soon became clear the atmosphere inside was of so poor quality that these soldiers became ill — if they did not lose consciousness outright, they'd be incapacitated for about an hour recovering from the noxious fumes, when exposed to fresh air on leaving the tank.

Therefore, in the summer of 1917, Lieutenant G.R. Rackham was ordered to design an armoured vehicle specifically for troop transport. The early design process was complicated by a demand that the vehicle could also be fitted with sponsons, converting it into a more modern tank than the Mark V, in case the Mark VIII tank design proved a failure. This is why the type was still designated as a tank, a "Mark IX" succeeding the Mark VIII. That requirement was soon dropped, and in September 1917 Armstrong, Whitworth & Co. in Newcastle-upon-Tyne began constructing two prototypes of a pure transport vehicle, which could also serve as a supply tank. The prototypes were approved the following year. At the time it had become clear that a possible alternative, the stretched Mark V* tank, was not really suited for infantry transport. Therefore two hundred vehicles were ordered of the Mark IX, to be built by the tractor manufacturer Marshall, Sons & Co. of Gainsborough, Lincolnshire.

Only three vehicles were finished at the time of the Armistice, and only 34 were built in total.


As there was no time for a completely new design, the Mark IX was based on the Mark V, with the hull lengthened to 9.73 m. The 150 hp Ricardo engine was moved to the front, the gearbox to the back and the suspension girders left out entirely. This created an inner space 4 metres long and 2.45 m wide, enough room for thirty (officially even fifty) soldiers or ten tons of cargo. To ensure sufficient stiffness for the chassis, the floor was reinforced by heavy transverse girders. The infantry inside had to contend with the control rods for the gears running along the roof and the drive shaft through the middle. No seats were provided for them.

Internal arrangement of a Mark IX tank

The crew proper consisted of a driver sitting on the left and a commander sitting to the right of him (the first time for a British tank, showing adaptation to the traffic conditions in France), a mechanic and a machine gunner who could man a gun in a hatch at the back. A second machine gun was fitted in the front. Along each side of the hull were eight loopholes, through which the soldiers could fire their rifles, making the Mark IX also the world's first infantry fighting vehicle. Two of the loopholes were in the two oval side doors on each side.

Despite the use of thinner (10 mm) armour plate, the weight was still 27 tons and the speed only 4 mph (7 km/h). The tank could also carry supplies in a tray on the roof behind the commander's armoured observation turret (being the highest point at 2.64 metres), while towing up to three loaded sledges.

Rackham tried to improve internal conditions by putting a large silencer on the roof together with ventilation fans; there was no separate engine room however. Because of this lack of compartmentalisation it is questionable whether the project reached its original goal of designing a vehicle capable of delivering a squad of infantry in fighting condition.

Operational history and project[edit]

The Mark IX tank at The Tank Museum

The Mark IX's were used for some years after the war. The type was named The Pig as the low front of the track looked like the snout of one. One of the first three was used as an armoured ambulance. One other was rebuilt as an amphibious tank by the staff of the test base at Dollis Hill. It already had large bulk; this was improved by fitting drums at the front and sides. Long wooden boards were attached to the track links but at one side of the board only; as they reached the curve of the track they would project out propelling the tank through the water. Pictures were made of a floating tank in Hendon Reservoir at 11 November 1918, the very day of the Armistice. There is an oral tradition that this vehicle was named The Duck, but there is a strong suspicion as to its veracity.

The last Mark IX survives at The Tank Museum, Bovington.


  • TANK: A History of the Armoured Fighting Vehicle By Kenneth Macksey and John H Batchelor Copyright 1970 ISBN 0-684-13651-1 Page 46
  • TANK Facts and Feats: A Guinness Superlatives Book By Kenntih Macksey 3rd Edition Copyright 1980 Page 61