What advantage did different planes give in different wars?

I've a homework assignment where i have to find out what planes were used in different wars (WWI, WWII, Vietnam, War in Iraq) and find out what the differences were and how they gave an advantage according to the battle, for example in WWII aircrafts were designed to fly at lower altitudes because their primary use was to aid ground forces while today planes are made to fly at incredible altitudes so that they can get a wide range of intelligence and attack while still being far enough away from fire.

if anyone has any ideas or information it would be greatly apreciated, thanks.

Here are four web sites that will help you answer your question. Also, go to the library they still allow you to check out books for free :)

http://library.thinkquest.org/3142/

http://facultystaff.vwc.edu/~dgraf/milit...

http://www.hist.unt.edu/military_web.htm

http://www.history.com/search.do?searchT...

You already understand the advantage to ground troops in using airplanes.
There are also dogfights, and in WWI, that happened a lot, close up.
This continued thru Korean War, and Vietnam war, where US planes, mostly from aircraft carriers dominated the sky.

When one side has domination of the air, then it's harder for the other side to move troops and supplies, without being seen and attacked. Planes act as spotters for artillery and seaboard guns to hit land areas under enemy control.

Today in Afghanistan and Iraq, they are using unpiloted drones, which have cameras on them, and are guided by those using remote controls, often thousands of miles away, and they can drop bombs accurately from several thousand feet up.

The USA has more aircraft carriers than any other nation, and this makes our "air force" very mobile. But, also we have more reliance on guided missiles today, like the Tomahawk, that can be launched from underwater submarines too.

So, the biggest change in past twenty years or so, is more reliance on unpiloted, remotely controlled missiles and drones.
Satellites high in outer space, can select targets and are used for incredibly accurate targeting.