– Given that marching across no-man’s land was virtually a death sentence, why did nations with parallel trenches not just start digging trenches forward towards each other, to avoid going over the top?


For instance, given kilometres of trench networks which ran close to each other, sometimes only hundreds of meters apart, why did soldiers from each side not just begin digging new trenches towards the enemy from places across the length of their existing trench, so that they could eventually break through without sacrificing thousands of lives running across open killing fields?

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Digging tunnels is extremely difficult. Add to that the fact that no man’s land was turned into a muddy bog and there’s bombs going off a few feet above you constantly the risk of a cave in is very high. Also what would happen when you eventually do breakthrough? You’ve got a direct line into their trench but that also gives them a direct line into your trench.

Because it’s very hard to dig trenches without being seen and as soon as you are seen digging a trench towards the enemy trenches they would send artillery (or if you were close enough grenades)

You also have to remember that even if you did you’re only going to be able to dig a fairly narrow trench towards where the enemy has a fairly wide trench – which gives the defending side an advantage in the number of troops they can safely send to capture that section of trench

They did try sometimes though – sometimes it worked too but more often than not it didn’t

They’d also sometimes try to dig under each others trenches

At various points (particularly during WW1) the trenches were insanely close to each other.

They did!

There were extensive competing tunnel and trench systems, including teams trying (and sometimes succeeding) in tunneling under the enemy lines so they could set up an enormous quantity of explosives and blow the enemy up from below. As you can imagine this was a significant effort, and was highly dangerous for the tunnel diggers, particularly as if the other side knew you were tunneling because they’d be listening out for the work and would try dig a tunnel to install explosives to blow up your tunnel team.

They did also do things like you describe, but a hazard it is that a trench that can get your side to the enemy trench also functioned very effectively as a means for your enemy to get into your trench…

Another hazard was being way out like that made the trench digging team highly vulnerable to attacks – either a direct assault (in which case if successful the enemy have a direct line into your trenches) or via grenades/mortars/etc.

You are still exposed to artillery fire if you do that. When you are very close you are exposed to hand grenades too. There is also the risk that the enemy let you dig forward and attack the trench and then use the trench to attack you.

You can’t do that in secret and a narrow trench that can protect you from artillery fire is very narrow so the amount of people that can move along it is limited. You can also fire along the trench and throw grenades. The one that defends on a pendular trench has a advantages

There is an alternative to building tunnels but even then the number of people you can move forward is low so it was used to place explosives below the enemy line so you can destroy them. https://en.wikipedia.org/wiki/Tunnel_warfare

Marching across no-mans land like was done in WWII is not as stupid as it looks. That was done with a creeping barrage that move forward slowly, we talk about 50-100 meters every few minutes. Your side marches forward to be just outside the lethal range of the artillery that covers the enemy trenches. The moment is slow you can time it with the artillery. It is pre planed so you time your moment to stay just outside lethal range.

The idea is that you can suppress the enemy and keep them away from the trenches in an underground shelter and they do have not enough time to emerge to defend it before your troops are in there too.

It is not the case the enemy can just go out when the artillery no longer hits on top of them. You can have it moving back and forward so that if they emerge the artillery move back over them again. Only your side knows the plan so you can move forward the last time the artillery hits the enemy trench.

You do not march forward if there is no moving barrage you move forward quickly to minimize exposure time.

Since no one’s mentioned it, I feel like a perpendicular trench (once noticed by the enemy) would offer a lot less protection. As long as they can aim horizontally, the distance and angle etc wouldn’t matter much. If the trench is full of soldiers it seems like it would be like shooting fish in a barrel. With a parallel trench they’d really have to dial things in to get a direct hit down into the trench.