scouting
the wright brothers
Bombing the enemy troops.
If the question is "What in the First World War" then the answer is planes (Gotha's).
about 730 planes
flamethrower,tank,machine,planes
how many planes id germany have at start of World War 1
Go to the related link(WW 1 war planes) for a comprehensive list of WW 1 war planes
at least 1
Trench warfare was mostly used, and planes were used to locate enemy positions
Being part of England, they flew British planes.
over 100 us planes