My understanding was that artillery was brutally effective but supply lines couldn’t keep up. So you would blast a trench, and it would be quickly abandoned by

My understanding was that artillery was brutally effective but supply lines couldn’t keep up. So you would blast a trench, and it would be quickly abandoned by the defenders, but when you tried to actually get your guys in to capture it they would just storm it from their backup trench and you would lose because you had no way to support the offensive.