Mk IX

[David]

The need for armoured cross-country troop and supply carriers was recognized when the first tanks were built. In practice this was carried out by standard or slightly modified heavy tanks - satisfactorily in the case of the supply carriers which were converted Tanks Marks I-IV or Gun Carriers, but very unsuccessfully for carrying men unaccustomed to travelling in the confined, poorly ventilated and rocking interior of a tank. It was decided in 1917, therefore, to produce a tank specially as a supply or infantry carrier. The design was entrusted to Lieutenant G. J. Rackham: work was commenced in September and the prototype of Tank, Mark IX completed by Sir. W. G. Armstrong, Whitworth & Co. in the following year. Full-scale production (which was undertaken by Marshall Sons & Co. of Gainsborough, Lincolnshire) started too late for Mark IXs to be used in action, although thirty-five were completed by the end of 1918.
The Tank, Mark IX could carry up to fifty infantrymen or ten tons of supplies. The hull was an elongated version of the lozenge profile of the Mark V, etc. but without the sponsons, which were replaced by two large oval doors on each side. The fixed armament consisted only of two Hotchkiss machine-guns, but a row of loopholes was provided on each side of the hull to allow infantry being carried to use their own light weapons. Mechanically, the Mark IX was based on the Mark V. In order to give a large clear space in the middle of the tank, the Ricardo 150-h.p. engine was placed immediately behind the driver's/commander's compartment although the gearbox and, of course, final drive was at the rear of the tank. This left the centre compartment (13 ft 6 in. long and 5 ft 3 in. wide) clear except for the cardan shaft running through the centre.
The Mark IX had a loaded weight of 37 tons and the same engine as the Mark V so, not surprisingly, the top speed was low (only 4 m.p.h.) compared with contemporary British heavy tanks. However, it would have played a useful part had the war continued longer and development of this type of machine - which was then neglected for the next twenty years - would have been followed.

An experimental amphibious version of the Mark IX, fitted with long cylin­drical air drums each side, was first tried out on the Welsh Harp at Hendon, near London, on Armistice Day, 1918.
The nicely preserved Mk IX in the fine photos here can be seen in the splendid Tank Museum in Bovington, in the UK.