The First World War Was the First Modern War

This statement is partially valid. To assess the validity of the statement two aspects of the war should be taken in consideration. During the First World War modern, heavier and weapons more lethal than ever before were used for the first time. Traditional weapons were redesigned, making each soldier deadlier than before. However old tactics going back to the 19th century were used to combat the enemies.
The First World War is often referred to as "a 20th century war fought with 19th century tactics". It was the first "world" war in the true sense of the word, involving the whole of Europe and even, towards its end, the United States of America.
"Modern" it became indeed when one considers the new, deadlier weapons that were developed just before and during this war: Tanks, airplanes, machine guns, chemical weapons are the most widely known by the general public.
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