In the beginning was chaos, consisting of a watery mass. Only two beings existed—Apsu, the Deep, and Tiamat, the universal mother. These two represent the two formative elements from whose union the gods were created. First Lakhmu and Lakhamu were born, then Anshar and Kishar, and after a long interval the other great gods. Tiamat, after having brought forth the gods, conceived a hatred for them and created a large number of monsters to aid her in a battle against them and gave the command to her son Kingu. She bore: “giant snakes, sharp as to teeth, and merciless—with poison she filled their bodies as with blood.” Anshar sends his son Anu against Tiamat, but he is afraid to face her. After Ea also has been sent in vain, Marduk offers to take up the fight, but first demands to be recognised by the other gods as their champion. Anshar summons the great gods to a feast, informs them of all that has taken place, and calls on them to appoint Marduk as their defender. The gods do so and hail him with the following words (the translation of the Assyrian texts is based upon that of Jensen
Thou art the most honoured among the great gods
Thy fate has no equal, thy decree is Anu.
Marduk, thou art most honoured among the great gods
Thy fate has no equal, thy decree is Anu.
From now on thy word shall not be altered,
To put up and to lower, shall be in thy hand;
What goes out of thy mouth shall be established
Thy decree shall not be resisted.
No one among the great gods shall overstep thy boundary
........
Marduk, thou our avenger,
We give thee dominion over the whole world.
To test his powers the gods place a garment before Marduk and tell him to bid it disappear and come back again at his word. When he has accomplished this prodigy the gods are pleased and exclaim “Marduk is king.” The avenger after equipping himself for the fray goes out to meet Tiamat and her host, taking with him his thunderbolt, spear, and net; he is followed by seven winds, which he has created. We take up the story again at the point where Marduk challenges Tiamat to battle:
“Stand! I and thou let us fight together—”
When Tiamat heard these words
She became like one demented, and lost her senses.
Then cried out Tiamat wild and loud
Her limbs trembled to their very foundations,
She said an incantation, and spoke a formula,
And of the gods of battle, she asked their weapons.
They drew near, Tiamat and Marduk, wise among the gods,
They advanced to battle, came near to fight—
Then the lord spread out his net and surrounded her.
He let loose the evil wind that was behind him.
When Tiamat opened her mouth to its full extent,
He sent the evil wind into it, so that she could not close her lips.
Filled her belly with terrible winds
Her heart was … and she opened wide her mouth.
He seized the spear and pierced through her belly
Cut through her inward parts, and pierced her heart.
He overcame her and destroyed her life,
Threw down her body and stood upon it.
When he had killed Tiamat, the leader,
Her might was broken and her host scattered
And the gods, her helpers, who went at her side
Trembled, were afraid, and turned back.
After Marduk had dealt with the minor rebels
He returned to Tiamat, whom he had conquered
He cut her in two parts like a fish
He put up one half of her as a cover for the heavens,
Placed before it a bolt and established a watchman—
And commanded him not to let her waters come forth.
The rest of the legend deals with the creation and has been mentioned elsewhere. Professor Gunkel