Battle of the Eclipse

The Battle of the Eclipse (or Battle of Halys) was fought in the early 6th century BCE in Anatolia (present-day Turkey) between the Medes and the Lydians. According to ancient Greek historian Herodotus, the battle was interrupted by "day turning into night" – presumably a solar eclipse – and the result was a draw which led to both parties negotiating a peace treaty and ending a six-year war.

Herodotus' account
Herodotus writes that in the sixth year of the war, the Lydians and the Medes were engaged in an indecisive battle when suddenly day turned into night, leading to both parties halting the fighting and negotiating a peace agreement. Herodotus also mentions that the loss of daylight had been predicted by Thales of Miletus. He does not, however, mention the location of the battle.

"Afterwards, on the refusal of Alyattes to give up his suppliants when Cyaxares sent to demand them of him, war broke out between the Lydians and the Medes, and continued for five years, with various success. In the course of it the Medes gained many victories over the Lydians, and the Lydians also gained many victories over the Medes. Among their other battles there was one night engagement. As, however, the balance had not inclined in favour of either nation, another combat took place in the sixth year, in the course of which, just as the battle was growing warm, day was on a sudden changed into night. This event had been foretold by Thales, the Milesian, who forewarned the Ionians of it, fixing for it the very year in which it actually took place. The Medes and Lydians, when they observed the change, ceased fighting, and were alike anxious to have terms of peace agreed on."

As part of the terms of the peace agreement, Alyattes's daughter Aryenis was married to Cyaxares's son Astyages, and the Halys River (present-day Kızılırmak River) was declared to be the border of the two warring nations.

Modern interpretations
If the description by Herodotus of the event is read as a solar eclipse, then based on modern astronomical calculations it can be identified with the Eclipse of Thales, yielding an exact date for the battle: May 28, 585 BCE. For the location of the battle, some scholars assume the Halys River, as it was located in the border region between both kingdoms. As Isaac Asimov notes, this would be the earliest recorded eclipse the date of which was accurately determined in advance of its occurrence.

However, such a reading is disputed by various scholars. For example, the known astronomical knowledge available of that time was not sufficient for Thales to predict the eclipse. Also, the eclipse would have occurred shortly before sunset at any plausible site of the battle, and it was very uncommon for battles to take place at that time of day. Furthermore, based on the list of Medean kings and their regnal lengths reported elsewhere by Herodotus, Cyaxares died 10 years before the eclipse.

An alternative theory regarding the date of the battle suggests that Herodotus was recounting events that he did not personally witness, and that furthermore, the solar eclipse story is a misinterpretation of his text. According to this view, what happened could have been a lunar eclipse right before moonrise, at dusk. If the warriors had planned their battle activities expecting a full moon as in the previous few days, it would have been a shock to have dusk fall suddenly as an occluded moon rose. If this theory is correct, the battle's date would not be 585 BCE (date given by Pliny based on date of solar eclipse), but possibly September 3, 609 BCE, or July 4, 587 BCE, dates when such dusk-time lunar eclipses did occur.