The "Battle Theme" plays whenever the player enters battle in a field area while fighting solo. It originally played only when the character drew his/her weapon, but in an update, it was changed to also allow players to hear the battle theme while a claimed monster is nearby. It is the fifth track in the original soundtrack.
The "Battle Theme" is a downloadableBattle Music Sequence track. It curiously takes place in a cave area, despite Final Fantasy XI's "Battle Theme" not playing in dungeons, such as caves. It was released on July 19th in North America.