Were there any Celtic, Roman or Medieval ruins, remains and artifacts discovered accidentally during the construction of these trenches or from shell craters?
Followup question: what happened to all of the trenches dug in Europe during WWI after the war ended? I suppose they've all been filled up but if that's the case then how soon after?
Followup question: are there any instances where promising archeological sites were ignored/destroyed due to the tactical or strategic necessity of getting the trench dug and the forces bedded in?