Chemical warfare in WWI caused skin and respiratory problems.
earth damage
all of answer correct
the Germans' use of unrestricted submarine warfare
Trench warfare you twit!
Warfare in World War 2 are illegal and dangerous than warfare in World War 1.
Most of World War 1 was characterized by stalemates caused by trench warfare. This caused the war to drag out for longer than expected, and casualties extended to the civilian populations of some countries.
World War 1 introduced aerial warfare with airplanes and trench warfare
Bullets and bombs
The new weapons technology caused more destruction and casualties as well as ending trench warfare.
trench warfare chemical warfare
Trench Warfare.
possibly the british blockade which caused a famine in germany with about 750000 people dead