Vigilant: Go to the Civil War and study the Battle of Petersburg, VA, wherein the Union miners set off a mine (ever since called the crater) that blew a large section of the Rebel trenches; then followed with a infantry attack, in which the Union troops jumped into the crater, but could not get out (no ladders). The Rebels recovered an they killed thousands of men in that crater.
To understand WWI artillery get a book called "The Steel Wind" by Bruce Gumundsen (who was my instructor at the AMU.). THis book is the story of Oberst Georg Bruchmiller, the commander of all German artillery. The Germans called their barrages either Feuer Tanz/Walz (Fire Dance/Waltz) And Bruchmiller's fire schedules and techniques of mixing solid shot, shrapnel and poison gas were eventually copied by the tubemeisters of the AEF and are still part of the American doctrine.
VBR Billy H 09/12/00