Were machine guns really the cause of 'defensive' warfare? Rolling artillery barrages would send the front-line machinegunners hiding in the trenches. The wave

Were machine guns really the cause of 'defensive' warfare? Rolling artillery barrages would send the front-line machinegunners hiding in the trenches. The wave of attackers behind the artillery barrage, when moving quickly had a very good chance of capturing the front line of trenches. The problem that they would face is that rail-deployed reinforcements on the defender side would pour in as a counter-attack... And those recently-captured front-line trenches were, by design, indefensible from an attack from the rear. So you'd get lots of bloody attacks, with horrific loss of life, where all the territorial gains made in them would be lost in an equally bloody counter-attack. As a net result, the front is frozen, despite both sides taking turns attacking (And making brief territorial gains, that are immediately reversed). Artillery and railroads, not machineguns seem to be the major influences, there.