After consolidating his power over the Medes and creating a united empire, Kourosh turned his attention to the west. Croesus, the legendary and wealthy king of Lydia, looked upon this emerging power with concern. Trusting the ambiguous prophecy of the Delphic oracle, which had told him that "if he attacks the Persians, he will destroy a great empire," he attacked the Achaemenid territory around the year 547 BCE. He did not know that the great empire would be his own.
The first clash at the Battle of Pteria was bloody but inconclusive. Croesus, assuming that the fighting season was over, retreated to his capital, Sardis. But Kourosh, with a lightning-fast move and contrary to all conventional rules of warfare, crossed Anatolia with his army in the winter and surprised Croesus in his capital. In the Battle of Thymbra, Kourosh achieved a decisive victory by using an innovative tactic: placing camels in the front line to terrify the horses of the Lydian cavalry.
After a short siege, the wealthy city of Sardis fell, and the kingdom of Lydia was annexed to the Achaemenid realm. This victory not only placed the immense wealth of Lydia at Kourosh's disposal but also brought all the Greek-inhabited cities of the Anatolian coast under his rule, marking the first encounter between the two great civilizations of Iran and Greece. The fate of Croesus is uncertain; Herodotus tells a dramatic story of him being pardoned by Kourosh, while Babylonian sources refer to his being killed.
After the conquest of Lydia, Kourosh turned his attention to the largest and most magnificent city of the ancient world: Babylon. The conquest of Babylon in the year 539 BCE was more of a political and propagandistic success than a military victory. Nabonidus, the last king of Babylon, was deeply unpopular among the priests and the people due to his neglect of the city's main god, Marduk, and his long absence.
Kourosh intelligently used this internal discontent. Before the attack, he presented himself as a savior chosen by Marduk to restore order and justice. As a result, when the Persian army, led by Gubaru, reached the gates of Babylon, the city surrendered "without a battle." This peaceful conquest showcased the peak of Kourosh's political genius.
After entering Babylon, Kourosh issued a decree that was inscribed on a clay cylinder and became famous as the "Kourosh Cylinder." In this charter, he presents himself as a just and tolerant king who respects the religions and traditions of all the peoples under his rule. This policy, which also included allowing the Jews to return from their Babylonian captivity to their homeland, presented a new model of governing a multicultural empire that was in complete contrast to the brutal policies of the Assyrians.
After the conquest of Babylon, Kourosh spent the remaining years of his life consolidating his rule and campaigning in the eastern regions of the empire, expanding his territory to the borders of India and Central Asia. His death, around the year 530 BCE, is shrouded in mystery. Herodotus tells an epic story of his being killed in a battle with the Massagetae, while other sources refer to his natural death in Pasargadae.
Regardless of how he died, Kourosh left behind an unparalleled legacy. In less than two decades, he founded an unprecedented empire that stretched from the Aegean Sea to the Indus River. But more important than his conquests, he introduced a new philosophy of governance to the world; a philosophy based on justice, tolerance, and respect for diverse cultures that made his name immortal in history forever.