[Geek44]

The rhomboids (Marks 1-5 I think) came in two varieties. Those armed only with machine guns were termed 'females' and the ones armed with more traditional guns (I don't know the calibres) were 'males'.
These tanks had a dizzying top speed of five miles per hour and were terribly unreliable. Maneuvering was achieved through a complicated set of clutches that would either stop or re-engage one side of track to turn the tank. Early crews complained of heat, noise and 'bullet-splash' as incoming rounds shattered against the hull, small fragments entering the vehicle through gaps in the armour such as where machine guns were mounted.
IIRC tanks were first employed by the British at The Somme. Several were to be part of the first assault. Two turned up to participate several hours after zero-hour. Many were captured by the Germans and used against their former owners. In response to the tank, the first anti-tank weapons were developed. Among the first crude ideas used was ammunition with tungsten cores...the first AP rounds.