What made World War I a new kind of conflict?
The alliances made
The number of countries involved
The technology used
The particular governments involved
For the first time war involved the use of new technology such as aeroplanes, tanks and submarines. [ But it is trench warfare that remains the lasting image of World War I.
The increased power of the more modern weapons gave much greater advantages to defence, making it more difficult to win quick victories.
This led to often huge losses by the attackers - on the first day of the Battle of
the Somme 60,000 British soldiers were killed or wounded.
Trench warfare created an endless demand for men, munitions and supplies with often no apparent gains or victories.
There are no new answers.