The Arbalète sauterelle type A allowed bombs to be thrown into trenches beginning what was called what?
Trench warfare Trench warfare is a type of land warfare using occupied fighting lines consisting largely of trenches, in which troops are significantly protected from the enemy's small arms fire and are substantially sheltered from artillery. The most famous use of trench warfare is the Western Front in World War I. It has become a byword for stalemate, attrition, sieges and futility in conflict.
Trench shield Trench shields (also called Trench Boxes or Trench Sheets) are steel or aluminum structures used for protecting utility workers while performing their duties within a trench. They are customarily constructed with sidewalls of varying thicknesses held apart by steel or aluminum spreaders. Spreaders can be interchanged to match the width of the trench. The different materials and building designs lead to a variety of depth ratings, i.e. the depth of a trench that the shield can withstand a collapse without buckling. Depth ratings are determined by registered professional engineers.