These conditions caused some soldiers to develop ... But I’d probably feel different if I was a soldier in the trenches during World War One. WW1 SOLDIER JACK: Mud? Oh, we know all about mud ...

When we look back at World War One, the trenches are among the first things ... all of which powerfully put across the horrible conditions soldiers experienced. Dan Snow:You can of course visit ...

This story originally appeared in the August 2014 issue of National Geographic magazine as "The Hidden World of the Great War ... of the trenches above. A journalist visiting one of the caverns ...