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.
Unexploded ordnance Unexploded ordnance (UXO, sometimes abbreviated as UO), unexploded bombs (UXBs), or explosive remnants of war (ERW) are explosive weapons (bombs, shells, grenades, land mines, naval mines, cluster munition, etc.) that did not explode when they were employed and still pose a risk of detonation, sometimes many decades after they were used or discarded. UXO does not always originate from wars; areas such as military training grounds can also hold significant numbers, even after the area has been abandoned. UXO from World War I continue to be a hazard, with poisonous gas filled munitions still a problem. When unwanted munitions are found, they are sometimes destroyed in controlled explosions, but accidental detonation of even very old explosives also occurs, sometimes with fatal results.