The Kalinga war (ended c. 261 BCE) was fought in ancient India between the Mauryan Empire under Ashoka the Great and Kalinga, an independent feudal kingdom located on the east coast, in the present-day state of Odisha and northern parts of Andhra Pradesh. It is presumed that the battle was fought on Dhauli hills in Dhauli which is situated on the banks of Daya River. The Kalinga War was one of the largest and deadliest battles in Indian history.
This is the only major war Ashoka fought after his accession to the throne, and marked the close of the empire-building and military conquests of ancient India that began with the Mauryan Emperor Chandragupta Maurya. The war cost nearly 250,000 lives.