The Battle of the Eclipse or Battle of Halys was fought between the Medes and the Lydians in the early 6th century BC. The result was a draw which led to both parties negotiating a peace treaty and ending a six-year war. According to Herodotus, the appearance of a solar eclipse at the time of battle was interpreted as an omen, and interrupted the battle. Herodotus writes that in the sixth year of the war, the Lydians under King Alyattes and the Medes under Cyaxares 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. . As part of the terms of the peace agreement, Alyattes's daughterAryenis was married to Cyaxares's son Astyages, and the Halys River was declared to be the border of the two warring nations. Cicero mentions that Thales was the first man to successfully predict a solar eclipse during the reign of Astyages. He was the son and successor of Cyaxares and his reign began at the end of the war after Cyaxares' death. Pliny the Elder mentions as well that Thales had predicted a solar eclipse during the reign of Alyattes. If one reads the description by Herodotus of the event as a solar eclipse, then based on modern astronomical calculations it can be identified with the solar eclipse of May 28, 585 BC, hence yielding the exact date of the battle. 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 noted, this would be the earliest recorded eclipse the date of which was accurately determined in advance of its occurrence. However, such a reading is for a variety of reasons rather problematic and hence 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.
