While Leosydas shouted and tried to bring some order to the chaotic bloodfest the frontline soldiers or more like the 5,000 mercenaries were engaged in, events continued to unfold as the actions of the men there dictated it to, i.e. onto a very open, a very loud event.
There loud screams and chaotic shouts echoed throughout the hill and if that was not enough to alert the watchmen in the neighboring hills, well, at some point one brilliant man decided it would be nice to nice to have some light amidst the darkness and so decided to set one of the loghouses on fire.
And following him, many too felt that primal fascination all humans have with fire and lighting something with it.