In battle's wild Gandharva dance.
"Here the commentator explains: 'the battle resembled the dance of the Gandharvas,' in accordance with the notion of the Gandharvas entertained in his day. They were regarded as celestial musicians enlivening with their melodies Indra's heaven and the banquets of the Gods. But the Gandharvas before becoming celestial musicians in popular tradition, were in the primitive and true signification of the name heroes, spirited and ardent warriors, followers of Indra, and combined the heroical character with their atmospherical deity. Under this aspect the dance of the Gandharvas may be a very different thing from what the commentator means, and may signify the horrid dance of war." GORRESIO.
The Homeric expression is similar, "to dance a war-dance before Ares."