The Mark III Tank was a training tank that introduced some new features that were being developed for the Mark IV, and that was used to train tank crews at Bovington.
After the combat debut of the Mark I Tank it was clear that the idea had potential and that the design needed some improvements. Work began on what would become the Mark IV Tank, but in order to keep the production lines running and to provide training tanks, an order for 100 training tanks was placed. This was split into fifty Mark IIs and fifty Mark IIIs. The two types were largely similar, with relatively minor changes. All fifty of the Mark IIIs were built by Metropolitan with the first being completed in January 1917.
The Mark III had the same overall layout, engine and transmission as the Mark I Tank. It was made of slightly thicker metal (12mm instead of 8mm, although this was boilerplate rather than armour) and a narrower cab to allow for the use of wider tracks. Some were given a wider track shoe on sixth link, but these appear to have extended out from the side of the tank so didn’t use the extra width. The circular roof hatch of the Mark I was replaced with a wedge shaped structure with an armoured lid that allowed a crew member to look out of the tank with some protection.
Some later Mark III Males were given the short 6-pounder that was introduced on the Mark IV. This was less likely to get caught in rough ground than the long gun on the Mark I.
The Mark III also saw the Hotchkiss and Vickers machine guns used on the Mark I replaced with Lewis guns. These were smaller than the Vickers gun, and allowed the sponson on the female tanks to be redesigned. On the Mark I the large mounts for the Vickers guns meant that the entry hatch was tiny, making it different to get out of the tank in an emergency. The new Lewis gun sponson was only half the height, which allowed a large hinged flap to be installed below. This could be kicked open from the inside, making it much easier to get out in an emergency. However the Lewis gun proved to be unsuitable for use in a tank, as its cooling system blew hot air into the gunners face. When an improved version of the Hotchkiss machine gun appeared it soon replaced the Lewis gun, but the new sponson was retained.
All of the Mark III Tanks were used as training vehicles, mainly at the Tank Corps training base at Bovington.
Hull Length: 32.5ft
Hull Width: 13.75ft (male); 14.33ft (female)
Weight: 28 tons (male), 27 tons (female)
Engine: 105hp Daimler-Foster gasoline engine
Max Speed: 3.7mph
Armament (Male): Two 6-pounder guns and four machine guns
Armament (Female): Five machine guns