The front-line trenches ended up backed-up by second and third strains: 'help' and 'reserve' trenches. Interaction trenches connected all of them collectively. This method was strengthened with fortifications, underground shelters and thick belts of barbed wire. The diagrams we have presented only depict distinct samples of how these methods perform. https://machguns.com/product/lot-1442-hr-model-50-reising-class-iii-nfa-cr-fully-transferable/