The ritual of "Dewa Masraman" was documented perhaps for the first time by Beryl de Zoete and Walter Spies in "Dance and Drama of Bali" (1937), however when I visited in 2002 and videotaped it I was told by the village priest, Jero Mangku Made Mustika, that the ritual had been being performed every 210 days on the Balinese holiday "Kuningan" for at least 400 years without interruption. Popularly known as "Siyat Jempana" (Battle of Palanquins), the ritual is in my eyes not a battle at all, but rather a kind of lovemaking enacted ceremonially as a frenzied dance of palanquins. People say that the palanquins that bear idols inside locked wooden boxes ram each other, but I never witnessed any such violent sport. Rather, I saw the palanquins and the youths that bore them repeatedly converge almost amorously and spasmodically and then disband.
My understanding is that Dewa Masraman is one deity represented in six parts* that correspond to the six palanquins ("Jempana" or "Joli"). The "battle" of these palanquins then is not so much a battle between rival divinities, but rather the dramatization of some internal conflict within one spirit. While the goal of the ritual is to bless Dewa Masraman at the banks of the Unda river that flows near the temple and then return him to the temple, ironically it seems as though the god is reluctant to return to the temple. Much of the dance seems to be a physically dramatized negotiation, and then finally the palanquins are dragged in through the narrow angker (temple entrance) with what appears to be enormous strain and effort on the part of the dancers and other participants.
The pathos and catharsis of this ceremony are striking. I interpret it as a collective purification wherein the entranced participants are through Dewa Masraman negotiating their own inner conflicts so that they may return to purity and sanctity. *This phenomenon of a god in multiple parts is not isolated. In the Vegetarian Festival of Thailand the "Nine Emperor God" is a Taoist divinity considered to consist of nine different emperors, and various rituals at that festival reflect this belief.