The Thundergun.
the most dramatic weapon was the airplane
Sonar was not introduced in World War 1.
In World War 2 the Germans introduced the V2 rocket, a terrifying new offensive weapon. In WW1 poison gas was considered the most terrifying weapon.
Hydrogen bomb
The Thundergun.
Guns
bomb
Atomic bombs
Atomic bombs
Atomic bombs
Atomic bombs
Atomic bombs
The atomic bomb
Tokyo in Japan
New stuff? well, the idea of using poisonous gas as a weapon is new during that period
Because it was a new weapon, not previously known to mankind.