Explain the connection between the Industrial Revolution and the onset of Trench Warfare in the West at the beginning of WWI. Why did the soldiers end up in trenches? What did military commanders not understand about defensive firepower?

A trench system may begin simply as a collection of foxholes hastily dug by troops using their entrenching tools. These holes may subsequently be deepened so that a soldier can safely stand up in one of them, and the individual foxholes may be connected by shallow crawl trenches. From this beginning a system of more permanent field fortifications may be constructed. In making a trench, soil from the excavation is used to create raised parapets running both in front of and behind the trench. Within the trench are firing positions along a raised forward step called a fire step, and duckboards are placed on the often muddy bottom of the trench to provide secure footing.