World War I did have machine guns, so you can rule that one out.
Mustard Gas was used, so you can rule that out for poison.
Automobiles were used, so you can rule that out.
Aircrafts were just new in 1917 at the end of the first world war. They couldn't carry anything but a pilot.
So I would say Aircraft Carriers.
Explanation:
377 square m.............
