In WW I, the water-cooled machine gun, and the squad automatic rifle were the most modern weapons, honorable mention to the American Colt M1911 pistol. In WW II, the list is very lengthy.
The M1 Garand rifle was the most modern military shoulder rifle of all the warring nations, and the bazooka was a new type of weapon during WW II. WW II was the first war to use submachine guns extensively, but they had been invented right after World War I, hence were not "new". Newer weapons continued to be introduced - especially by the United States and Germany - all the way through WW II.
balls & wieners
Mustard gas
The submarine.
Man.
The French army used it first not as a weapon but as a deterrent. it is similar to modern day tear gas.
Poison Gas.
The most common one that was used as a weapon in World War 1 is called the Artillery
broken pistolthe zeppelin was the least important weapon in ww1.
The most common method was with artillery.It is NOT a biological weapon, it is a chemical weapon.
the tank
Nuclear weapons
Machine gun