Original sentence: The Livens Projector was a type of mortar that was used by the Allies in World War I for chemical warfare
Edited sentence: In World War One, the Livens Projector became the standard means of delivering gas attacks and it remained in the arsenal of the British army until the early years of the Second World War.The Livens Projector was a simple mortar-like weapon that could throw large drums filled with inflammable or toxic chemicals