So, here´s a thought I had. Say if magic had been discovered to be a real thing during, say, a decade or so prior to the Revolution. And by magic, I´m talking about, say, your standard Fantasy style magic of throwing fireballs, creating ranged explosions, telekinesis/telepathy. How would that have changed the face of both America, and world militaries? Would we have specialized companies of magic users?

It's a little hard to say, but you'd probably be looking at influences along the lines of the machine gun, depending.

Depending specifically on how prevalent magic was. If it was very uncommon, we might not see much in the way of difference at all: Military doctrine is driven only partially by innovation, and mostly on reliability/repeatability. This is why the United States Army did not adopt repeating rifles as the standard infantryman's weapon in 1873; (likely unfounded) concerns over ammunition supply and fire discipline meant they decided to stick with the single shot Springfield 1873.

If it was common, then it would be considered a force multiplier in the same way a machine gun is. There would probably not be specialized companies of magic users, but rather there would be specialists embedded at the unit level in the same way that machine guns are.

There would probably also have been an arms race to see who could develop the best spells fastest, but that's hardly an unusual possibility.

5975725 We would have made machines to do magic better than any human and accidentally have destroyed the world.