Siddhartha once was a boy of a powerful king. One day, he was roaming around when he found... a question, I don't know what? but he wanted the answer of that question, so he went out of the palace, into the woods to search for the he sat there under a tree, he felt the cool breeze, sound of animals, gurgling streams, chirping birds etc. He felt so touched by the feeling of nature outside the four walls of his palace, he was overwhelmed, and felt the need to be a pure personality, other valuing riches and all, he wanted and became a saint and peacemaker as you said. H e was then known as Gautama Buddha.