Cuneiform texts make clear that the Neo-Babylonian king Nabonidus (r. 556–539 B.C.) elevated the status of the moon god Sin at the expense of Babylon’s long-time patron deity Marduk, who was the king of all Mesopotamian deities. Nabonidus’ own inscriptions record that he clashed with the powerful priests of Marduk, and compositions written after the king was deposed by the Persian ruler Cyrus the Great (r. 559–530 B.C.) claim that the people of Babylon were scandalized by Nabonidus’ treatment of the god. If the texts are to be believed, Babylonians were especially dismayed that Nabonidus failed to celebrate the New Year rituals that were central to Marduk’s cult and to maintaining Babylon’s role as Mesopotamia’s chief city. Cyrus is said to have restored Marduk to his rightful place, but it’s likely people in other ancient Mesopotamian cities such Nippur may have recalled a time when Marduk himself was an interloper among the gods. “We need to remember that Marduk wasn’t always the great deity he was known as in the Neo-Babylonian period,” says Heidelberg University Assyriologist Hanspeter Schaudig. “He himself was once a god-killer.” 

In the third millennium B.C., Babylon was a small, obscure city. Marduk was a minor deity with equally obscure origins who seems to have been associated with agriculture and canals, and whose symbol was a spade. During this period, Nippur was Mesopotamia’s most sacred city, and its god, Enlil, wielded ultimate divine power. But in the second millennium B.C., especially during the reign of Hammurabi (r. ca. 1792–1750 B.C.), Marduk became an ever more consequential god. As Babylon’s influence grew, he assumed the powers and name of Addu, a storm god who was the patron deity of the city of Halab, modern-day Aleppo. 

Toward the end of his reign, Hammurabi defeated the ruler of the city of Eshnunna, which had been allied with the Elamite people who lived in modern-day Iran and posed a constant threat to Babylonia. At the same time, cuneiform texts celebrated Marduk’s victory over Eshnunna’s patron god Tishpak. Marduk then appropriated Tishpak’s chief symbol, the lion-dragon hybrid beast known as mušhuššu, or “furious snake,” with whom he would be associated for the rest of Babylonian history. Depictions of mušhuššu that decorated the city’s famed Ishtar Gate, which was built more than 1,000 years later, still commemorated Marduk’s victory over Tishpak, and Babylon’s over an important ally of Elam. 

By the twelfth century B.C., Marduk played a central role in an updated Mesopotamian creation story known as the Enuma Elish, which later cuneiform tablets preserve in many versions. The standard account of this narrative legitimized the god’s position as ruler of the divine pantheon once headed by Enlil and explains how Babylon supplanted Nippur as Mesopotamia’s most important religious center. In the creation myth, Marduk is a young warrior god and the only deity willing to do combat with Tiamat, the goddess of the sea and embodiment of chaos. In return for facing Tiamat, the gods agree to make Marduk king of the gods. Upon killing the goddess, Marduk claims his throne and brings order to the cosmos and creates the world. He makes Babylon the first city and home to his Esagila temple, where Marduk lived in the form of his sacred statue. This version of the Enuma Elish completely ignores Enlil and his sacred city of Nippur, erasing Babylon’s rival from the creation story. 

Babylon’s status as Mesoptomia’s chief city waxed and waned, and it was sometimes captured by outside powers, events Marduk’s followers needed to account for. One text known as the Marduk Prophecy recounts how Babylonians sometimes angered the god. Their city was consequently then seized by enemies such as the Hittites from Anatolia and Elamites, each of whom “godnapped” Marduk by capturing his sacred statue and taking it back to their respective capitals. The prophecy refers to these events as the travels of Marduk, as if the god chose to be borne away to foreign lands. Those second millenium B.C. sojourns were brought to an end by the Babylonian king Nebuchadnezar I (r. ca. 1125–1104 B.C.), during whose reign the Enuma Elish may have first been written down. The king sacked the Elamite city of Susa, reclaimed Marduk’s statue, and brought it back home to Babylon, once again establishing it as Mesopotamia’s capital of both earthly and cosmic rule.