I had a memory of a training camp in France, around 1915.
They had us learn to dig trenches, working at it all day long.
An officer stood over me. “Put your back into it! They’re shooting at you! Dig! Dig!” he shouted practically in my ear. The ground had the consistency of peat and came loose in dense clumps. It stuck to everything and had a slight acid smell to it.
The field had been the site of some mayhem in medieval times; several of us found medieval arrow heads and I think someone else found a broken spear tip. We were either in or near Normandy, where I may have trained as a knight more than 700 years earlier.
We had a model redoubt about 100 square yards by the time we were done that day. It was a very basic trench, with little more in the way of refinements than firing steps and small wooden shelters.