Elephant warfare

Hi,

I just saw this movie and I liked it. But I was wondering a couple of things about elephant warfare.

The first thing is firing small cannons from the elephant. Some people say it is not possible and other think that elephants turn nuts when a gun is fired a couple of meters from their heads. I disagree, since when you scale it down, it is comparable from firing a handgun from a horses back and that can be done with the proper training. But does anyone has info about this?

The second question is; did elephants ever charge into a meelee? Or where they more used to just be there; as a dangerous creature that you better stay away from. And didn't the way the drivers fought remember anybody about the classical NY traffic jam with cars all packed together being angry at each other?

Well, that's about it. Thanks in advance if someone could answer my questions :)