List the new weapons of World War 1. which of these weapons had the greatest impact and why?

Tommy gun(trench broom)

heavy machine gun

shorter rifle=more mobility(kar 98)

biological warfare(artillary=mustard gas shells)

steel helmet

special tactics(trench warfare)

the heavy machine gun probably had the most impact because of its ability to mow down a line of men continuosly.

the artillay want far behind(over a billion shells spent during ww1)