Ashoka is famous for accepting Buddhism after watching the brutality in Kalinga War.

Ashoka was born in 265 B.C. He was the great Indian emperor. He was the grandson of the great Changragupta Maurya. Ashoka ruled over an empire on very large area that covered two-thirds of the Indian continent. He was the most famous of the Mauryan kings and was one of the greatest Hindu rulers of India, who later got embraced Buddhism.
The capital of the Ashoka's Empire was located in the city of Pataliputra (now known as Patna, the capital of Bihar in the eastern region of India). 

He was a very brave ruler and a good administrator. He was the younger son of the King Bindusara and was given the throne soon after the kings death because he was loved and respected by his subjects and by his ministers. His grandfather, Chandragupta, had set out to conquer the weaker kingdoms around his kingdom to expand the territory of his people in 324 BCE, and was the first to rule over a unified India.

After 8 years of his rule, King Ashoka decided to attack Kalinga (Orissa). This was the first and last battle that Ashoka ever fought. Though Ashoka won the battle he was horrified by the loss of life and death of so many soldiers. So he moved towards Buddhism.