My understanding of WW1 had always been that its style of trench warfare was stable throughout the entire war. That is to say, the only defense against the new weaponry was to dig trenches, and the only way to capture trenches was to throw a few thousand men at them, at which point, you may have gained a few hundred yards. This continued until Germany ran out of resources.
What ultimately moved us past trench warfare, the story goes, was the improvement of the tank.
But a few years ago, I listened to a podcast (which may as well have been called Testosterone Drenched History, the actual name escapes me) that claimed that tactics had been updated near the end of the war; the war was becoming more mobile, ground was being transferred more quickly. It did not get into details.
I stumbled across this webpage (https://www.warhistoryonline.com/world-war-i/breaking-the-deadlock-machine-gun.html) that credits light machine gun units (with ample supplies of grenades) for breaking the stalemate.
And a piefed user supplied this somewhat cryptic (to someone who doesn´t read German Norweigan) diagram of how to take out a machine gun nest.
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[translation provided in comments: suppressive fire and toss in a grenade, repeat]
What is the true story of the tactical situation at the end of WW1?


Combat exercise 3: Break in and fighting in the fortifications interior (24). The goal of this combat exercise is to practice an effective technique to break into enemy firing positions and fight in the interior of the fortifications. This is the teams most demanding task in war. We make a difference between three different targets.
Image captions from L to R:
Targets with individual positions. Targets with built systems of positions. Targets in areas with buildings
SD 3a Take pit* (Breaking into firing position), Crawl & throw and Crawl & Assault Image caption: It is the soldier who is best positioned to throw, that throws the grenades. The division of 1st and 2nd is only made to make explaining the exercise easier. (*trench that is big enough for a couple of soldiers maybe)
Phase 1: Initializing
1st orders: Take pit. Make ready shock/splint (I guess HE/frag grenade). 1st shoots single shots at the enemy position to keep the enemy heads down until the grenades are in the air. 1st evaluates and communicates if possible HIT or MISS for the grenade. Thereafter shifts focus to the depth when the grenade has hit. The procedure is repeated if the first grenade misses. 2nd replies: ACKNOWLEDGED. Announces Shock/Splint and throws hand grenade into the pit.
Phase 2: Assault
After the grenade has exploded the pit is assaulted. 2nd orders: Assault (2nd is the one who threw the grenade). 2nd focuses on the pit. 1st follows 2nd and looks at the area around the target. 1st only shoots when spotting targets. Without hand grenades the task has to be done with (small arms) fire. Suppressing fire then has to be effective until the one who is supposed to take the pit can peep over the edge and can fight (clear the pit) with rapid or automatic fire.
Yes, then I guess the real challenge in WW1 is getting into range to throw the grenade.
Thanks for the translation!
The challenge was not attacking. Tactics evolved to allow for successful attacks, eg creeping barrage covering the advancing infantry until they could jump into the enemy trench. The issue was holding onto the ground you took. You had to transport supplies and drag your artillery forwards through the mud of no man’s land after an attack. The enemy could reinforce and then counter attack using roads and rail that was not blown to bits yet.