Who is the remorseful Mauryan emperor embraced Buddhism after a terrible battle?

The remorseful Mauryan emperor who embraced Buddhism after a terrible battle is Ashoka the Great. Following the bloody battle of Kalinga, which resulted in significant loss of life, Ashoka experienced deep remorse over the suffering caused by his conquests. This led him to adopt Buddhism and promote non-violence, compassion, and tolerance throughout his empire, becoming a key figure in the spread of Buddhism in India and beyond.