Developed just before the outbreak of WWII, the A20 heavy tank was initially designed by the British with trench warfare in mind. The tank was hastily redesigned to adapt to the new mobile form of warfare and later became the basis of the Churchill tank.
WWII Churchill tank deploying fascines to cross ditch - GIF
British WWI Mk tank diagram - image
Churchill ARV towing a German Mark IV tank - GIF
Hobart's Funnies - photos
WWII Churchill tank converted into mine clearer