Ashoka had given ample evidence of his ability as a soldier and a statesman even before becoming the king. He was the Viceroy of Ujjain and when there was a rebellion in Taxila and the situation went out of hands of Susima, his eldest brother, who was the viceroy there, Ashoka was sent there to quell the rebellion. To begin with Ashoka followed the footsteps of his illustrious grandfather Chandragupta Maurya and launched upon a career of conquest and aggression. The Buddhist text Divyavadana mentions his conquest of Khasa country. But the only conquest referred to in his edicts took place in the ninth year of his coronation.
In the thirteenth year of his reign and eight years after his coronation Ashoka made war against Kalinga, modern Orissa including Ganjam and included it into the Magadhan Empire. The conquered country was formed into a viceroyalty with its headquarters at Tosali. Parts of Kalinga were within the dominions of the Nanda Kings. After the fall of Nanda Empire, Kalinga had severed its connection with Magadha.
If we go by the story of a general revolt under Bindusara during which Taxila revolted, it is not “unlikely that Kalinga like Taxila” remarks Dr. H.C. Roy Chaudhury “threw off the allegiance of Magadha during the reign of that monarch”. But Dr. Roy Chaudhury also mentions the evidence of Pliny, who based his work on Megasthenes’ Indika that at the time of Chandragupta Kalinga was an independent kingdom with an army of 60,000 foot soldiers, 1,000 horsemen and 700 elephants which was in “Procint of War”. Thus the evident of Pliny belies the presumption of a revolt by Kalinga during the time of Bindusara for it was already independent during Chandragupta’s time.
We know turn to the probability of Kalinga becoming independent after the fall of the Nanda rule in Magadha. Chandragupta Maurya’s pre-occupation in setting the newly acquired sovereignty and building up the administration left no time at his disposal to turn the conquest of Kalinga.
A pertinent question that still remains is why Ashoka instead of trying to conquer the Chola and the Pandya countries which his father tried to subdue proceeded to conquer Kalinga. Andhra which lay south of Kalinga had been conquered by Bindusara but when he proceeded to conquer the Chola and the Pandya countries, Kalinga an ally of the Cholas and the Pandya’s attacked Bindusara from the rear and became the cause of Bindusara’s failure. Thus Kalinga was an enemy of the Mauryas both because its breaking away from the Magadhan Empire and particularly because of the turning in an ally of the countries Bindusara wanted to conquer. It was, therefore, perhaps supremely imperative to reduce Kalinga to complete subjection”.
The major cause for the conquest of Kalinga was a populous and strength. Historians have described about the military strength of Kalinga. R. C. Majumdar remarks that Kalinga was a populous and powerful state. It had thrived on maritime trade. Thus wealth both human and material accounted for the strength of the country and her spirit of independence has been demonstrated by her assuming independent status after taking advantage of the confusion consequent upon the overthrow of the Nandas and her jealous guarding of independence by not allowing Bindusara to conquer her allies, the Cholas and the Pandyas.
The huge causalities of the war as described in the Rock Edict XIII with one hundred fifty thousand taken prisoners, hundred thousand slain and as many number dead bear out hugeness of the army of Kalinga and its highly populousness. Obviously, the Kalinga King must have added to his army strength such a strong country remaining in precinct of war on the border of his dominions could certainly not be a matter of indifference to any emperor. Ashoka, therefore, felt the need of subjugating Kalinga.
The conquest and annexation of Kalinga left Samrat Ashoka free to carry out his policy of conquest of Chola and Pandya countries to complete the conquest of the whole of the Indian peninsula. But soon after the Kalinga War Ashoka became a Buddhist. For a year Ashoka was lukewarm but thereafter he began strenuous efforts for promoting the Dhamma for his mind was fired by ennobling aspiration of becoming supreme on earth not through territorial conquests but through conquest of Dhamma and which stood for love, humanity, and nonviolence.