Why was World War 1 so devasting?

World War I was devastating due to the unprecedented scale of destruction and loss of life, with an estimated 16 million deaths and 21 million wounded. The introduction of modern warfare technologies, such as machine guns, tanks, and chemical weapons, led to horrific battlefield conditions and mass casualties. Additionally, the war's extensive trench warfare resulted in a prolonged stalemate, causing immense suffering and psychological trauma among soldiers. The geopolitical ramifications reshaped borders and societies, setting the stage for future conflicts.