The earliest event of Asoka’s reign that we find recorded in his Inscriptions is his conquest of Kalinga (Orissa), which proved to be a turning point in his life. Asoka conquered Kalinga eight years after his coronation – i.e., in the ninth year of his reign.
After this conquest Asoka ceased to indulge in wars of aggression. Why, instead of invading the Chola and Pandya countries of the South, Asoka decided to conquer Kalinga is not clear.
Probably located between the Mauryan dominions in Bengal and Andhra, independent Kalinga was “a thorn in the body-politic of the Mauryan Empire” and as such could have posed threat to his dominions. Moreover, the kingdoms of Southern India were on very friendly terms with the Mauryan Empire.
The conquest of Kalinga was of importance to Mauryan Empire both from strategic and economic point of view. It stood in the way of the southern routes from the Ganges Valley, and it was also a powerful maritime area, which if included could become a convenient source of income to the Mauryan empire. After the conquest of Kalinga further territorial conquest was almost unnecessary for Asoka.
The 13th Rock Edict vividly describes the horrors and miseries of this war and the deep remorse it caused to Asoka. “A hundred and fifty thousand persons were deported, a hundred thousand were killed and many times that number perished.”
“On conquering Kalinga the Beloved of the Gods felt remorse, for when an independent country is conquered, the slaughter, death and deportation of the people are extremely grievous to the Beloved of the Gods and weighs heavily on his mind.”
After the conquest of Kalinga, Asoka realised the actual gravity of the war and wrote: “Today if a hundredth or a thousandth part of those people who were killed or died or were deported when Kalinga was annexed were to suffer similarly, it would weigh heavily on the mind of the Beloved of the Gods.”
The Kalinga war had a profound effect on the public policies and personality of Asoka. After this war he decided never to wage any other war and also instructed his sons and grandsons “never to wage such war”.
In the 13th Rock Edict Asoka declares that a true conquest is not that by arms but a conquest by piety and virtue (Dharma Vijaya). After the conquest of Kalinga, Asoka devoted his life to the moral and material welfare of the people and reformulated his public policies accordingly.
The violence of war seen in all its nakedness made Asoka adopt non-violence and peace as the creed of his life. He came to change his personal religion and adopted Buddhism. The Kalinga war was the last political event of his reign.