Assurbanipal (to the Greeks, Sardanapalus, r. 668 - ca. 627 BCE), third son of Esarhaddon and grandson of Sennacherib, was the sixth and last great king of Assyria. His eldest brother, Sín-nãdin-apli, had been designated crown prince of Assyria. His second brother, Šamaš-šum-ukín, was the crown prince of Babylonia. As the third son, Assurbanipal had no right to expect a throne. However, when Sín-nãdin-apli died in 672, his father made Assurbanipal the heir to the Assyrian throne.
Assurbanipal's newly established position as the Assyrian crown prince put him at odds with Šamaš-šum-ukín. However, Esarhaddon seems to have wanted to avoid conflicts of interest and internecine rivalry by splitting what had previously been two distinct kingdoms.
That was not the way events panned out.
Assurbanipal seems to have positioned himself to play a significant role after his father's death. Even before he became crown prince, he gave orders to officials. "[N]o governor had been appointed and no prefect had been installed" without his permission. (Fincke, Babylonian Texts p. 118 n. 52).
As he set about establishing his legitimacy, he seems to have been following in his father's footsteps.
Esarhaddon was also a younger son. He was appointed crown prince by his father Sennacherib "on demand of Aššur, Sîn, Šamaš, Běl and Nabû, Ištar of Nineveh and Ištar of Arbela". The promotion came after he had established his credentials through extispicy.
So his father presented Assurbanipal's rise as pre-ordained:
To avoid a possible civil war in the future, Esarhaddon "convened the people of Assyria, great and small, from coast to coast, made them swear a treaty oath by the gods and established a binding agreement to protect my crown princeship and future kingship over Assyria." (Fincke, Babylonian Texts p. 119).
Once he had secured his position, he seems to have set about preparing himself for the future.
His term as crown prince was relatively short. While we do not know how old Assurbanipal was when he became crown prince in 672, he was on the throne four years later.
Materials in the archive suggest that by the time he assumed the kingship. Assurbanipal had mastered the "complete scribal art", including the "craft of the diviner, the secrets of heaven and earth," and the "wisdom of Šamaš and Adad." Unlike his predecessors, he was not forced to depend on what his scribes or officials told him or read to him. Since he could read the messages himself, he was harder to manipulate.
Official sources present Assurbanipal as a learned, scholarly man who read Sumerian or Akkadian cuneiform tablets regardless of their age. On the other hand, some of the king's correspondents seem to have judged his ability less favourably.
"Sometimes, they explained a rather common word of the omen literature by a synonym or an alternative expression. Some scribes even transferred the learned kind of writing that uses logograms into syllabic Akkadian writing or gave the pronounciation of these logograms; someone who was familiar with Sumerian would have known how to read these sentences . . . The obliging manner of the scribes to explain certain words or expressions might indicate that the king himself read the reports; the scribes did not expect the king to have the expert knowledge of divination." ((Fincke, Babylonian Texts p. 121).
According to his royal inscriptions, Assurbanipal had a particular interest in old tablets. He was proud of his ability to read "stone tablets from before the flood," which is remarkable considering the change in the cuneiform script over the millennia. According to one of his prism inscriptions, Assurbanipal was not only able to read these old scripts but was also "enjoying the writing on stones from before the flood."
He also claimed to have mastered the art of warfare, although he does not seem overly keen on fighting. While he remained in Nineveh, he stayed in continuous contact with his officials and agents. He used written directions to control his empire and direct military campaigns.
During his reign, the Assyrian empire reached its largest extent, encompassing Upper Egypt.
However, years of resentment and hostility between Assurbanipal and his brother, Šamaš-šum-ukín enlisted several allies to form an anti-Assyrian coalition. The move proved disastrous for Babylon.
After a two-year siege by Assurbanipal's forces, the city fell, Šamaš-šum-ukín died, and the Assyrians did their best to erase any trace of him.
Assurbanipal then ruled Babylonia himself, with direct access to all the Babylonian temple archives. When Assurbanipal created his extensive royal library in the citadel of Nineveh, he included Babylonian tablets into the collection. Some tablets may have originated in Babylonian libraries. Others could have been the work of Babylonian scribes in Assurbanipal's service.
Sources:
Chambers Biographical Dictionary
A Dictionary of World History
Jeanette C. Fincke, The Babylonian Texts of Nineveh: Report on the British Museum's "Assurbanipal Library Project"
Philips World Encyclopedia