The Kalinga War was a war fought between the Mauryan Empire and the state of Kalinga. Kalinga was an important kingdom because it controlled the trade routes with Southeast Asia. Because of this, Ashoka, the Mauryan king, wanted to capture it. Therefore he lead his huge army to Kalinga in 261 BC.
The Kalingans also led an army to the warfield. The small army of Kalinga was not a match for Ashoka's mighty army. Though the Kalingan army fought hard, soon the whole Kalingan army had collapsed. There were more than 100,000 deaths on both sides. The battlefield was bloody with dead or injured soldiers, crying orphans and widows.
Although he won the war, Ashoka realized the futility of war. He vowed never to fight again. He converted to Buddhism and he dedicated his later life to help his subjects.