I mean sometimes they dug at night, thats one way
but you also have to realize that the trench lines weren't that close to each other, basically when the war ground to a stop both armies stopped at just outside of direct fire range and started digging in, no man's land was often a few football field's wide, with trees and hills and stuff between the two lines, things that got flattened by 4 straight years of shelling into the muddy hell you see in movies but in the first days of digging that would have blocked views
from there they slowly dug closer toward the enemy but like I said they were never close enough to reach out and touch
See I knew they were never that close but I do also remember the reason why I had the question to begin with was our teacher said that the trenches could be as close as 10 meters away from each other in certain areas which just made me think of these two dudes awkwardly digging pretending not to see each other although if they were digging at night it'd probably be easier to politely ignore each other
