sandbags piled up in a trench to protect soldiers and narrow slits to look out and shoot from

sandbagged army bags barricade battlefield communication trench entrench entrenchment excavating excavation first world war fortification foxhole great ground gunny sack hessian bag jute loopholes military protection raids resilience restraint sacking sandbag sandbags security soldierly soldiers strategy trenches trenching warfare wartime ww1 wwi