The trench stalemate is the result of a fairly complicated interaction of weapons which created a novel tactical problem. The key technologies are machine guns, barbed wire and artillery (though as we’ll see, artillery almost ought to be listed here multiple times: the problems are artillery, machine guns, trenches, artillery, barbed wire, artillery, and artillery), but their interaction is not quite straight-forward. The best way to understand the problem is to walk through an idealized, “platonic form” of an attack over no man’s land and the problems it presents.

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So, the first problem: artillery. Neither side starts the war in trenches. Rather the war starts with large armies, consisting mostly of infantry with rifles, backed up by smaller amounts of cavalry for scouting duties (who typically fight dismounted because this is 1914, not 1814) and substantial amounts of artillery, mostly smaller caliber direct-fire¹ guns, maneuvering in the open, trying to do fancy things like flanking and enveloping attacks to win by movement rather than by brute attrition (though it is worth noting that this war of maneuver is also the period of the highest casualties on a per-day basis). The tremendous lethality of those weapons – both rifles that are accurate for hundreds of yards, machine guns that can deny entire areas of the battlefield to infantry and the artillery, which is utterly murderous against any infantry it can see and by far the most lethal part of the equation – all of that demands trenches. Trenches shield the infantry from all of that firepower. So you end up with parallel trenches, typically a few hundred yards apart as the armies settle in to defenses and maneuver breaks down (because the armies are large enough to occupy the entire front from the Alps to the Sea).

The new problem this creates, from the perspective of the defender, is how to defend these trenches. If enemies actually get close to them, they are very vulnerable because the soldier at the top of the trench has a huge advantage against enemies in the trench: he can fire down more easily, can throw grenades down very easily and also has an enormous mechanical advantage if the fight comes to bayonets and trench-knives, which it might. If you end up fighting at the lip of your trench against massed enemy infantry, you have almost certainly already lost. The defensive solution here, of course, are those machine guns which can deploy enough fire to prohibit enemies moving over no man’s land: put a bunch of those in strong-points in your trench line and you can prevent enemy infantry from reaching you.

Now the attacker has the problem: how to prevent the machine guns from making approach impossible. The popular conception here is that WWI generals didn’t “figure out” machine guns for a long time; that’s not quite true. By the end of 1914, most everyone seems to have recognized that attacking into machine guns without some way of shutting them down was futile. But generals who had done their studies already had the ready solution: the way to beat infantry defenses was with artillery and had been for centuries. Light, smaller, direct-fire guns wouldn’t work² but heavy, indirect-fire howitzers could! Now landing a shell directly in a trench was hard and trenches were already being zig-zagged to prevent shell fragments flying down the whole line anyway, so actually annihilating the defenses wasn’t quite in the cards (though heavy shells designed to penetrate the ground with large high-explosive payloads could heave a hundred meters of trench along with all of their inhabitants up into the air at a stretch with predictably fatal results). But anyone fool enough to be standing out during a barrage would be killed, so your artillery could force enemy gunners to hide in deep dugouts designed to resist artillery. Machine gunners hiding in deep dugouts can’t fire their machine guns at your approaching infantry.

And now we have the “race to the parapet”. The attacker opens with a barrage, which has two purposes: silence enemy artillery (which could utterly ruin the attack if it isn’t knocked out) and second to disable the machine guns: knock out some directly, force the crews of the rest to flee underground. But attacking infantry can’t occupy a position its own artillery is shelling, so there is some gap between when the shells stop and when the attack arrives. In that gap, the defender is going to rush to set up their machine guns while the attacker rushes to get to the lip of the trench:first one to get into position is going to inflict a terrible slaughter on the other.

Now the defender begins to look for ways to slant the race to his advantage. One option is better dugouts and indeed there is fairly rapid development in sophistication here, with artillery-resistant shelters dug many meters underground, often reinforced with lots of concrete. Artillery which could have torn apart the long-prepared expensive fortresses of a few decades earlier struggle to actually kill all of the infantry in such positions (though they can bury them alive and men hiding in a dugout are, of course, not at the parapet ready to fire). The other option was to slow the enemy advance and here came barbed wire. One misconception to clear up here: the barbed wire here is not like you would see on a fence (like an animal pen, or as an anti-climb device at the top of a chain link fence), it is not a single wire or a set of parallel wires. Rather it is set out in giant coils, like massive hay-bales of barbed wire, or else strung in large numbers of interwoven strands held up with wooden or metal posts. And there isn’t merely one line of it, but multiple lines deep. If the attacker goes in with no preparation, the result will be sadly predictable even without machine guns: troops will get stuck at the wire (or worse yet, on the wire) and then get shot to pieces. But even if troops have wire-cutters, cutting the wire and clearing passages through it will still slow them down … and this is a race.

Bret Devereaux, “Collections: No Man’s Land, Part I: The Trench Stalemate”, A Collection of Unmitigated Pedantry, 2021-09-17.

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1. Direct fire here means the guns fire on a low trajectory; you are more or less pointing them where you want the shell to go and shooting straight at it, as you might with a traditional firearm.

2. The problem with direct-fire artillery here is that you cannot effectively hide it in a trench (because it’s direct fire) and you can’t keep it well concealed, so in the event of an attack, the enemy is likely to begin by using their artillery to disable your artillery. The limitations of direct-fire guns hit the French particularly hard once the trench stalemate set in, because it reduced the usefulness of their very effective 75mm field gun (the famed “French 75” after which the modern cocktail is named [Forgotten Weapons did a video covering both]). That didn’t make direct-fire guns useless, but it put a lot more importance on much heavier indirect-fire artillery.