Ishme-Dagan I (; died 1765 BC) was a monarch of Ekallatum and Assur during the Old Assyrian period. The much later Assyrian King List (AKL) credits Ishme-Dagan I with a reign of 40 years; however, it is now known from a limmu-list of eponyms unearthed at Kanesh in 2003 that his reign in Assur lasted around 11 years. According to the AKL, Ishme-Dagan I was the son and successor of Shamshi-Adad I. Also according to the AKL, Ishme-Dagan I might have been succeeded by his son Mut-Ashkur.
Biography
Family
thumb|256px|left|A map of the [[Ancient Near East showing the geopolitical situation around the Assur (light brown) near contemporary great powers such as: Eshnunna (light blue), Yamhad (dark blue), Qatna (dark brown), the First Dynasty of Babylon (yellow), and the Third Mariote Kingdom (shortly before the conquest of the long-abandoned town of Shubat-Enlil c. 1808 BC by the Amorite conqueror Shamshi-Adad I.)]]
Ishme-Dagan I's father, Shamshi-Adad I, was an Amorite king, originally of Terqa (in Syria), who seized control of Assyria around 1808 BC.
Shamshi-Adad I ruled from Shubat-Enlil. Shamshi-Adad I placed his oldest son (Ishme-Dagan I) on the throne of Ekallatum. Shamshi-Adad I placed his youngest son (Yasmah-Adad) on the throne of Mari. Ishme-Dagan I ruled the south-eastern region in Upper Mesopotamia. Ishme-Dagan I's realm of influence included the city-state of Assur.
Correspondence
A number of letters relating the familial relationships between Shamshi-Adad I and his two sons have been excavated, and these letters provide a glimpse into the tensions of this family of rulers. 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. Shamshi-Adad I's correspondence with his younger son is not as generous, and Ishme-Dagan I appears to have picked up his father's censure of his younger brother and contributed to it. In one letter, Ishme-Dagan I asks his brother, “Why are you setting up a wail about this thing? That is not great conduct.”
Death of Shamshi-Adad I
Although his father counted Ishme-Dagan I as politically astute and a capable soldier, commending him as he berated Yasmah-Adad in their letters, Ishme-Dagan I was not able to hold his father's empire for long after his father died. 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:
This letter led historians to believe that Yasmah-Adad held the throne of Mari for a while after his father died. However, this letter was proven to actually be from Ishme-Addu of Ashnakku, (written to Ibal-Addu of Ashlakka), thus disproving many chronologies that had been based on the letter. Ishme-Dagan's reputation with Hammurabi fluctuated with Hammurabi's goals, and there is some evidence that Hammurabi sent troops to aide Atamrum, one of Ishme-Dagan's rivals, during Babylon's war with Larsa.