Also, I would finish some "unfinished" business with Cuba, N. Korea, Vietnam...................

Yeah, definitely. I would make the US win in Nam ( as Eric explained, though, that war was actually lost on the home front ).
I would the Bay of Pigs Op work, would definitely make Israel invade Khomeini's Iran back in 1979 and... is that three wishes only, or... ?

Yep, unfortunatelly we lost it on home front. From military standpoint, with attrition, we were deffinitely winning the war, but on home front we lost it..........................

i would change chanchellorsville, the south would still of won and jackson would of survived that might of had a huge effect on gettysburg itself, considering i'm geographically from way down south (southern hemisphere)

Bullecourt (10,000 dead) and fromelles (5,553 out of 6000 in a feint attack at night) in ww1

I wouldn't change Pearl Harbor...it was the very suddenness of the attack that galvanized the American people and, more than any other factor, led to American entry into WWII. By turning Peal Harbor into a "normal" battle rather than a sneak attack, you delay the entry of America into the war and very likely change the outcome.

If I had to change a military battle, I would say probably either Balaclava or Little Big Horn.

In the former, I can see no strategic or even tactical reason for the 300 men of the Light Brigade to disdain the offer of allied support and charge against a force more than 10 times their size -- there is a difference between honor and stupidity.

The latter is changed by the simple expedient of making sure the 7th cavalry had proper ammunition. Most of the men in Custer's command were able to fire only one or two shots before their weapons jammed...somebody had saved money by exchanged their regulation rounds with ones of wrapped brass, which generally ruptured and welded itself to the breech after a couple of shots. Proper ammunition would have allowed many of them to hold out until Major Reno arrived with the rest of the 7th Cavalry. (George Custer probably would still have died -- he was apparently killed early in the fighting. But his brother Captain Tom Custer may very well have survived.)

Nam, dont think I need to explain this one.

Id have the Terrorists fight themselves to the death, and when it seems like a few will survive send in some Soldiers and Marines to finish them off.

Evening troops.

I'd go back to the Falklands conflict, 1982, and get Col 'H' Jones VC to duck, rather than getting slotted in the back by that Argie MG position. I feel that British military doctrine could've gone in a different direction if 'H' had survived. We use Manouvrism, which I think 'H' would've advocated, but I feel a more 'fire-power and aggression' doctrine may've evolved.

Failing that, I'd go back to Agincourt; not to change the result, 'cos we won. I'd just provide the Welsh Archers with mortars and grenade launchers - just to make the victory all the more decisive...!