How did machine guns, artillery, trenches, and barbed wire make the Western Front difficult to attack?

On the Western Front, the combination of machine guns, artillery, trenches, and barbed wire created a defensive environment that made traditional offensive maneuvers nearly impossible.

• Machine Guns: The development of automatic weapons allowed defenders to sweep open terrain with a "storm of steel," making it impossible for infantry to survive an advance across exposed ground.1
• Artillery: Revolutionized by recoil mechanisms, artillery enabled rapid, high-volume fire. It was used to pulverize enemy positions and clear defensive lines, but it also forced troops to seek refuge in deep, underground dugouts, rendering them difficult to eliminate even with heavy bombardment.12
• Trenches: Armies solidified into continuous, multi-layered trench systems spanning hundreds of miles. These systems included communication trenches that allowed for the rapid movement of reinforcements to seal gaps, ensuring that even if a first line was breached, the attacker faced further resistance.13
• Barbed Wire: Thick belts of barbed wire, sometimes hundreds of yards deep, acted as a formidable obstacle that slowed or halted advancing infantry, leaving them vulnerable to machine-gun fire.13

Together, these elements forced a stalemate where the tactical defense became significantly stronger than the offense.13