Final answer:
Mary is considered a 'dauntless' girl because she has displayed heroism, courage, and endurance in helping her oppressed race.
Step-by-step explanation:
Mary is considered to be a 'dauntless' girl because she has shown heroism in her character and has demonstrated courage and power of endurance in facing danger and death to relieve human suffering. In the context of the passage provided, she is compared to historical figures like Joan of Arc, Grace Darling, and Florence Nightingale who displayed similar bravery and resilience. Despite her lowly station in life and dark skin, Mary has become a leader and deliverer to her oppressed and suffering race, striving to guide them from the land of Bondage to the promised land of Liberty.