Trench Foot, a major problem during WW1. By later in the war, the causes (foot immersion/damp) were identified and a variety of means of mitigation devised. This is why by WW2, there was a thorough routine for nearly all armies to include foot care - and these had enough NCOs who remembered WW1 to know why it was important and enforce the regs.
However, it became an issue in the Falklands, and at various music festivals. in the 1990s (see link).
I can see this being an issue where troops may lose amounts of spare kit (spare dry socks) in periods of lengthy, chilly damp weather (Fall, Winter, Spring) spent in the field.
Trench foot will damage the foot, whereas
Chilblains will just produce misery.
Uncle Ted