Ishme-Dagan I's father, Shamshi-Adad I, was an Amorite king, originally of Terqa (in Syria), who seized control of Assyria around 1808 BCE.
Ishme-Dagan I is called, “A forceful soldier not afraid to risk his own skin.” This was a quality which allowed Shamshi-Adad I to rely on him unhesitatingly.
To Ishme-Dagan I's east were the warlike, nomadic, pastoral peoples inhabiting the foothills of the Zagros Mountains.
An instance of defeat occurs in a year-name coined by the King Dadusha of Eshnunna which commemorates a victory over an army led by Ishme-Dagan I.
Ishme-Dagan I eventually lost most of his domain, and was reduced to holding Ashur and Ekallatum, despite waging several counter offensives to try to regain the upper Khabur area.
The year-name of the fifth year of Ibalpiel II's reign (indicating some reverence to Shamshi-Adad I at his death) suggests that Eshnunna had become subservient to the Ekallatum.
Ishme-Dagan I wrote a letter to his brother, after Ishme-Dagan I assumes their father's throne and the rule of all of Upper Mesopotamia, that he: “Has the Elamites on a leash as well as their ally, the king of Eshnunna.”[2]His confidence was overstated, however; as year-names of the eighth and ninth years of King Ibalpiel's reign indicate Eshnunna attacked and destroyed the armies of Ashur and Mari, and Ishme-Dagan I's control over his father's entire realm slipped, as his hold was reduced to the region of Ashur and Ekallatum.
One such letter caused issues in the chronology of the ancient near east, as it allowed historians to place dates on Hammurabi of Babylon.
Some evidence indicates that after his reduction in power, Ishme-Dagan I appeared to hold tolerable relations with Babylon, Eshnunna, and Mari.