only definitely prove that Shamash-shum-ukin held Babylon itself and its vicinity. The governors of some Babylonian cities, such as Nippur, Uruk and Ur, and the rulers in the Sea Land, all ignored the existence of a king in Babylon and saw Ashurbanipal as their monarch. Despite this, Shamash-shum-ukin had initially been positively inclined towards his brother, viewing him as his equal. In letters, Shamash-shum-ukin addressed Ashurbanipal simply as "my brother" (unlike how he addressed his father Esarhaddon, "the king, my father"). Although there are several letters preserved from Shamash-shum-ukin to Ashurbanipal, there are no known replies. It is possible that Ashurbanipal, on account of his network of informers, did not feel a need to write to his brother. By the 650s, Shamash-shum-ukin's opinion of Ashurbanipal had significantly deteriorated, owing to the increasing intervention and involvement of Ashurbanipal in Babylonian affairs, Ashurbanipal often delaying when help was needed, and growing dissatisfaction with his position relative to that of Ashurbanipal. A letter written during this time by Zakir, a courtier at Shamash-shum-ukin's court, to Ashurbanipal described how visitors from the Sea Land had publicly criticized Ashurbanipal in front of Shamash-shum-ukin, using the phrase "this is not the word of a king!". Zakir reported that though Shamash-shum-ukin was angered, he and his governor of Babylon, Ubaru, chose to not take action against the visitors. Aspiring to become independent of Ashurbanipal and free Babylonia under his own rule, Shamash-shum-ukin revolted in 652. According to later Aramaic-language legends, Ashurbanipal and Shamash-shum-ukin's sister Serua-eterat attempted to intervene and stop the two from fighting; after the war broke out the legends hold that she disappeared into self-imposed exile. The war between the brothers lasted for three years. In addition to resenting Ashurbanipal's overbearing control, Shamash-shum-ukin's revolt was also facilitated by the certainty of support in the south: the Babylonians constantly resented Assyrian control and the rulers of Elam were certain allies, always willing to join anyone who waged war against Assyria. Inscription evidence suggests that Shamash-shum-ukin addressed the citizens of Babylon to join him in his revolt. In Ashurbanipal's inscriptions, Shamash-shum-ukin is quoted to have said "Ashurbanipal will cover with shame the name of the Babylonians", which Ashurbanipal refers to as "wind" and "lies". Soon after Shamash-shum-ukin began his revolt, the rest of southern Mesopotamia rose up against Ashurbanipal alongside him. The beginning of Ashurbanipal's account of the conflict reads as follows: According to the inscriptions of