History of the Battle of Halys in 585 BC, when an eclipse stopped a battle

A solar eclipse stopped a battle between two Anatolian peoples on May 28, 585 BC in the Battle of Halys (or “Battle of the Eclipse”) fought between the Medes and Lydians on the banks of the Halys River (today's Kizilirmak) in present-day Turkey. The eclipse was interpreted by the two sides as a bad omen and for this reason the battle stopped. We know that the battle took place on May 28 of that year precisely because we are aware of the fact that on that day a solar eclipse was visible in Anatolia: this makes the battle of Halys the oldest historical event of which we know with certainty the date.

The Anatolian Peninsula, today entirely occupied by Turkey, hosted numerous advanced peoples and civilizations in the first millennium BC. For this reason, it has often been the scene of bloody conflicts. At the beginning of the 6th century BC, they were among the peoples competing for control of the Peninsula the Lydians and the Medes. In the year 585 BC an eclipse of the Sun occurred while the armies of the two peoples were fighting near the river Halys, put an end to hostilities. The Greek historian Herodotusto whom we owe the knowledge of this episode, also says that the eclipse had been predicted by Thales of Miletus. But was it possible, with the astronomical knowledge of the time, to calculate eclipses?

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The Battle of Halys

The Battle of Halys was fought by two peoples settled in the Anatolian Peninsula: the Lydians, probably descendants of the Hittite people, and the Medes, of Iranian origin. Lydians and Medes, led respectively by the sovereigns Aliatte and Ciassarre, entered into conflict in 590 BC. C. for the control of central Anatolia. The war continued with mixed success for six years. The August 28, 585 BC the two armies faced each other near the Halys river (we do not know the precise location of the battle because the river, called today Kızılırmakis over 1000 km long).

The Halys River (credits Kmhkmh)
The river Halys and the kingdoms of the Lydians and Medes. Credits: Kmhkmh.

The fight was in full swing when a total eclipse of the sun brought darkness to the battlefield. The soldiers, fearing that the blackout was a sign sent by the godsthey immediately stopped fighting.

We know this story thanks to the narration of the Greek historian Herodotus. Here is his story:

In the sixth year of the war a battle took place in which an eclipse occurred; when the fighting had already begun, suddenly the day became night. And Thales of Miletus had predicted this change of day to the Ionians (i.e. the Greeks who lived on the Anatolian coast), also providing the year of the event. When the Lydians and Medes saw themselves overwhelmed by the night in broad daylight, they stopped fighting and became inclined to make peace with each other.

It is not known whether hostilities resumed after the eclipse, but it is certain that shortly afterwards the two kingdoms signed an agreement peace agreement, also sanctioned by the marriage of the son of the king of the Medes, Astyages, with the daughter of the king of the Lydians, Arieni. According to some modern scholars, the two rulers also established that the Halys River marked the border between their respective territories. Both the kingdom of the Lydians and that of the Medes, however, were destined to last a short time: after a few decades they were incorporated byPersian Empire.

Was Thales able to predict the eclipse?

The Battle of Halys is the first historical event of which we know the exact date. Eclipses, in fact, can be calculated with precision and the only total eclipse of the period in question is that of May 28, 585 BC. NASA has calculated that the darkening had its peak (maximum darkness) over the Atlantic Ocean and that the cone of shadow reached the Anatolian Peninsula in the evening hours.

The eclipse of Thales (credits NASA)
The eclipse of Thales. Credits: NASA.

From Herodotus' story, however, another interesting element also emerges: Thales of Miletus, the famous philosopher and scientist of the 6th century BC. C., had predicted the eclipse of 585 BC, which today is in fact known as eclipse of Thales. Also two other ancient sourcesCicero and Pliny the Elder, state that the philosopher was able to predict the darkening of the Sun.

On this aspect, many modern historians they do not believe Herodotus' story, because the astronomical knowledge of the time did not allow us to calculate eclipses exactly, as we can do today. However, it cannot be ruled out that Thales was actually managed to predict the darkening of the Sun, at least approximately (he identified the year, as Herodotus says, but not the day), using astronomical knowledge developed by the Babylonians or on the basis of calculations on the cycles of eclipses.

Herodotus, Histories, 1, 74 Kevin Leloux, The Battle of the Eclipse (May 28, 585 BC): A Discussion of the Lydo-Median Treaty and the Halys Border, in “Polemos”, 19, 2, 2016