God's Troubadour, The Story of St. Francis of Assisi by Sophie Jewett (1861 - 1909)

Francis, a young Italian boy, is a merchant's son who is enthralled by the troubadour songs and tales of knights that his father brings back from his travels

He decides to become a knight, but after seeing the poor and suffering in the tragedies of war, he decides to give away all of his worldly possessions and become a troubadour for God