He was once an officer of Pasenadi, but later left the world. A conversation between him and Dhanuggahatissa it was which, overheard by Pasenadi's spies, led to Pasenadi changing his tactics and defeating Ajátasattu. J.iv.343; but see J.ii.403, where Dhanuggatissa's companion is called Utta, which is probably a wrong reading of Datta.
In the conversation Mantidatta is addressed as Datta, which was evidently his personal name, the prefix Manti being given him as the king's minister and to distinguish him from other Dattas.