The art of jedi Battle is a Force ability that allows a Force user to change the outcome of an entire battle (as in, war kind of battle, involving thousands or millions of soldiers) through his or her will alone. What it actually does is strengthen will and coordination in friendly forces, while doing the exact opposite with your enemy forces. An army with someone using Battle Meditation boosting it is almost impossible to beat, even when outnumbered. Very few Force users can use this ability for the most part, jedi in the old Republic receive more training in this technique than in the days of the clone wars due to fact that one of the bad things about war is that you lose focus on learning because of the need to just survive.
Generally, strong minded or Force-using opponents are not affected by the negative effects of Battle Meditation, but the positive bonuses to friendly troops make it worth using anyway. (Ex: Oppio Rancisis Battle Meditation would not have worked as well against the Chiss or Mandalorian army as it would against, say, Republic soldiers, because Mandalorians are generally strong-willed, strong-minded people. However, it would still be worth using, as the army facing said Chiss or Mandalorians would become a much more dangerous fighting force.)
During the time of the Clone Wars Jedi Master Oppio Rancisis was the Master Battle Meditation, Master Yareal Poof was also gifted in this art this is one of the reason that they were early targets and skillfully taking out. Palpatine was also gifted in the art of affecting Battles. A little known fact is that he had a force user during the battle of Endor named Grand Admiral Nial Declann that was gifted with this ability but when vader threw the emperor down the shaft Declann lost concentration due to his connection to the Emperor Palpatine and thus the rest is history.
The first mention of this Force power was in Tales of the Jedi, Jedi Master Odan-Urr Jedi Master Thon who taught perhaps the greatest Jedi in this field Nomi Sunrider (what a dope name) also the great Nubian Jedi Dace diath and Oss Wilum was also gifted with this gift. One thing that I must mention is that a jedi can not physically be in battle and use this gift as he or she must be in meditation hence the name, and also while they are in Battle Meditation they are vulnerable to attack.
I have not read of any gifted New Jedi Order in the art of battle meditation but Princess leia has used the technique in the dark empire comics and the jedi in the NJO series used a Battle Meld not to be confuse with this force power as a meld is similar but you are in battle and it affect a group of force users (by letting each other in one another mind) and not the enemy.