But, quite apart from this objection, there are small grounds for the belief that Sin-muballit was Rîm-Sin's vassal, or that they could have taken part in any united action at this period. In fact, every indication we have points to the conclusion that it was from a king of Larsa that Sin-muballit captured Isin in the seventeenth year of his reign.[41] Three years previously the date-formula for his fourteenth year commemorated his defeat of the army of Ur, and there are good grounds for believing that Ur was acting at this time with the army of the king of Larsa. For certain tablets are dated in the year in which Sin-muballit defeated the army of Larsa, and we may with some confidence regard this as a variant formula for the fourteenth year.[42] Thus, three years after his defeat of the king of Larsa, Sin-muballit followed up his success by capturing the city of Isin, which he commemorated in the formula for the seventeenth year. But he cannot have held it for long, for it must have been shortly retaken by Larsa, before being again recaptured in Hammurabi's seventh year.[43] Thus, in less than eleven years, from the seventeenth year of Sin-muballit to the seventh year of Hammurabi, the city of Isin changed hands three times. We may therefore conclude that the date-formula for Sin-muballit's seventeenth year, and those found upon the Tell Sifr tablets,[44] did not commemorate the fall of the Dynasty of Isin in Damik-ilishu's reign, but were based upon two episodes in the struggle for that city, which took place at a later date, between the kings of Larsa and of Babylon.