United Kingdom (1918)
Armored personnel carrier – 34 built
The world’s first APC
In late 1917, after studying reports of previous tank actions, the British general staff agreed that the Tank Corps lacked a specialized supply model, which could also function as a tracked armored personnel carrier. This was the tank Mark IX, based on the long Mk.V* (star) for simplicity of design. It was originally intended to be quickly fitted with armed sponsons if needed.
The idea of an APC was not new however. Colonel Estienne had already envisioned that the Schneider CA-1 would carry four men plus its crew right to enemy the trenches; and the Daimler Guinness Armored Trucks had been put into service a year earlier. But what is amazing is that there will be no tracked APCs until 1944, when the Allies experimented with turretless tanks, the “kangaroo“, which showed the need for specialized tracked, heavily armored and well armed vehicles for troop transport. This concept was fully developed during the Cold War.
As its first task was to carry troops at least to the first line of enemy trenches, engineers had to rework the Mk.V extensively. In itself the roomy Mk.V* was able to carry up to 10 infantrymen. However, they were confined in a highly gassy and extremely noisy fighting compartment. By the time they disembarked through the small doors not really suited for the task, they would have lost most of their combat abilities. But worst of all was that only ten infantrymen, even with full ammunition, would not last long as a fighting unit in itself when casualties amounted to hundreds in small spots.
The new requirement of the army command was the ability to carry no less than fifty infantrymen, or 10 tons of payload. A freight which could be placed either inside or outside, as part of the ammunition could be fixed in a roof housing for the superstructure. Another option was towing three carriages. Thus, the tank hull would have been significantly lengthened, while retaining almost the same height and width. The variant chosen had two large oval doors on the sides, fitted for effective mass landing and many pistol ports to fire from inside when approaching. Accordingly, the sponson idea was dropped and standard weapons restricted only to two 8 mm (0.31 in) Hotchkiss machine guns mounted on the sides.
The internal layout largely differed from the Mk.V*. In the process obtaining the largest compartment possible, the engine was shifted forward and the the gearbox backwards. Installed on the roof of the driver compartment was a low cylindrical commander’s cupola. The size of the central troop compartment was 13ft by 8 ft (4m x 2.45m). There was only 5ft 4inches (1.62m) of head room. Cramming fifty infantrymen inside was even in theory extremely difficult, so it was decided to accommodate only 30 men with full equipment.
The most important innovation was the installation of two roof exhaust fans to extract engine fumes. General protection remained similar to the Mk.V*. Enhanced armor protection could only be added at the expense of ride comfort (since it was unsprung), speed and mobility in general on soft terrain. As a result the frontal, sides and stern plates thickness did not exceeded 10 mm (0.39 in).
The wheeltrain consisted of 24 doubled rollers with blocked suspension, and front and rear guide wheel drive. Configuration was, as usual, of the rhomboid type, with metal links having a 521 mm (20.5 in) length shoe, and 194 mm (7.64 in) pitch. The upper part of the guide tracks was maintained by two tension rollers on each side.
Production of the Mark IX
Construction of the first prototype, dubbed “The Pig”, began at Marshall, Sons & Co. factory, Gainsborough, in June 1918 and completed in October. In tests the maximum speed was about 6.5 km/h (4.04 mph) but on rough terrain, this fell to just 1.3 km/h (0.8 mph). It could overcome trenches up to 3.8 meters (12.47 ft) large, and had a ground pressure of 1.95 kg/cm2.
According to other data, the maximum speed on road was 13.5 km/h (8.39 mph) and the range 89 km (55.3 mi). During trials several changes were ordered, one of which was the installation of a muffler near the fans. Nevertheless the Mk.IX failed to completely get rid of all the disadvantages of rhomboid tanks. The still uncompartmented engine and excessive weight caused poor mobility in the field. Nevertheless, the Mk.IX was produced since the Allies were determined to implement “Plan 1919”, the large-scale, heavily mechanized final assault on Germany.
Among other things, it called for supply and transport tanks. As a result before the armistice only two tanks had been ready for field tests on the Western Front, and only one of the first three then assembled was ready during October and November 1918. This sole Mk.IX was used in France as a sanitary conveyor. The remaining 34 Mk.IXs were finished after the war, and none would see actual combat although they participated in some exercises.
The world’s first amphibious APC
Shortly before the end of the war the first Mk.IX tested the ability to install floats for wading. As such, it was emptied, and reinforced on the flanks and fore part of the hull. The landing doors were sealed and gaskets used for pumping air.
Movement in water was provided by the rotation of the tracks, but special blades attached to the links were added for extra grip. In addition, a roof compartment housed part of the gear-cutting equipment, and the exhaust went through it. The amphibious Mk.IX was unofficially called “The Duck” and began a test series in November 11, 1918, conducted at Dolly Hill.
These were considered successful, although the tank was very slow and had low water buoyancy. In addition, this configuration precluded placement of access doors and the installation of a powerful weaponry. In November 1918 the tests were terminated.
The only amphibious Mk.IX was subsequently scrapped, but the data obtained in the tests helped later in the construction of more advanced amphibious tanks by Vickers.
So far, only one Mk.IX, noted IC 15, survived, which is now exhibited at the Bovington Tank Museum.
Mark IX specifications
|Dimensions||Length 31ft 11in (9.07m).
Width 8ft (2.44m).
Height 8ft 8in (2.64m)
|Total weight||37 tons|
|Crew||4 + 30 infantry men|
|Propulsion||Ricardo crosshead valve, water-cooled straight six petrol engine 150hp @ 1250rpm|
|Road Speed||4 mph (6.4 km/h)|
|Range||45 miles (72.42 km)|
|Trench Crossing ability||12ft 5in (3.8m)|
|Armament||2x 0.303 inch (7.62mm) Hotchkiss air-cooled machine guns|
|Armor||Max 10 mm|
|Track links||Length 8 inches (21.4cm)|
Width 1ft 7in (52.3cm)
|Side Hatch||Length 4ft (1.21m)|
Width 2ft 1in (63cm)
Mark IX in its regular livery, Somme sector, October 1918
Camouflaged Mark IX “Pig” in 1919.
Amphibious Mark IX “Duck” during tests, Devon.