Cyrus's plan is to catch the Lydian king unprepared for battle, but at Thymbra, Croesus has more than twice as many men as Cyrus.

The Lydians march out to meet Cyrus and quickly arm all the reserves there, before their allies are to arrive, which they never do.

According to Xenophon, Cyrus had one hundred and ninety-six thousand men in total, which was composed of from thirty thousand to around seventy thousand Persians.

This consisted of twenty thousand infantry which may have included archers and slingers, ten thousand elite infantry/cavalry, which may have been the Persian Immortals, plus twenty thousand peltasts and twenty thousand pikemen.

All except the archers and slingers are known to have carried small to large shields.

The others were: forty-two thousand Arabians; Armenians; and Medians, which amounted to one hundred and twenty-six thousand infantry.

There were also three hundred camel cavalry, three hundred chariots, and five to six siege towers, which were known to hold twenty men each.

It all amounted to over a thousand men men, partly because there was one citizen, and one soldier on each chariot.

Xenophon tells us that Croesus had an army of four hundred and twenty thousand men, which was composed of sixty thousand Babylonians, Lydians, and Phrygians, also Cappadocians, plus nations of the Hellespont.

This amounted to three hundred thousand men which included sixty thousand cavalry.

There were also one hundred and twenty thousand Egyptians, plus three hundred chariots, which may have been at least five hundred men.

The numbers of the battle given by Xenophon, even if untrue, are considered within the realm of possibility, but less than half may have engaged in the actual battle.

Cyrus deploys his troops with flanks withdrawn in a square formation.

The flanks are covered by chariots, cavalry, and his best infantry and a newly organized camel corps.

This improvised camel corps is formed by camels taken from the baggage train, and its sole purpose is to disrupt the Lydian cavalry.

As Cyrus expected, the wings of the Lydian army wheel inward to envelop this novel formation.

As the Lydian flanks swing in, gaps appear at the hinges of the wheeling wings.

Disorder is increased by the effective overhead fire of the Persian archers and mobile towers, stationed within the square.

Cyrus now gives the order to attack, his flank units smashing into Croesus' disorganized wings.

Herodotus gives an account of the battle but does not give any numbers.

His account of the battle's progress and outcome, however, confirms that which Xenophon gives later.

After the battle, all the Lydian lands are annexed by the Persian empire, including the Greek cities of Ionia and Aeolis, which lead to conflict between Greece and Persia.

The surviving troops hole up in the nearby city of Ephesus and Sardis, which is captured after a short siege.

According to the Greek author Herodotus, Cyrus treats Croesus well and with respect after the battle, but this is contradicted by the Nabonidus Chronicle, one of the Babylonian Chronicles (although whether or not the text refers to Lydia's king or prince is unclear).