I heard the first British tank operations in WW1 frequently ended with its crew being unable to continue prematurely because of how goddamn hot it was inside them.
Not only that crew suffered from exhaust fumes inhalation, as the engine was open and in the centre of the tank, exhausts and proper ventilation came in later models.
Also British tankers did not wear helmets until 1943, they wore berets. It's the only time I've ever heard the phrase 'dislocated brain' to describe what happened to a churchill crew member after their tank rolled down a dune in North Africa.
A Mark IV, went up and down over a bunker knocking a crew unconscious during a demonstration for King George V in WW1. https://www.youtube.com/watch?v=h_0i_g2PpEU