What was trench warfare and how was it used effectively?

Trench warfare was a type of warfare used in wars through America’s history. They were used in the Civil War as well as WWIBand WWII. Basically, a group of men would dig a trench near where the other group they were fighting was. They would did trenches, advancing up and up as far as they could go. It helped gained the men extra miles and footage towards the other side, but it was not effective enough, many people died from this type of warfare.