Captain Robert FitzRoy (1805 - 1866) was a rising officer in the Royal Navy when he was appointed by the Admiralty to conduct a survey of the coast of South America in HMS Beagle. He wanted a naturalist to accompany the voyage, and also somebody who would function as a "gentleman's companion" for himself. Darwin's professor at Cambridge, John Stevens Henslow, recommended him for the post. Darwin and FitzRoy shared a small cabin at sea for five years. Darwin's nickname aboard ship was "Philosopher." FitzRoy was noted both for his qualities as a naval officer and commander, and also for his temper. When coming on watch, the relieving officers were accustomed to ask "If much hot coffee had been served out?" meaning, how was the Captain's temper?

    FitzRoy was a believer in the civilizing effects of slavery. Darwin recounted an incident, in which FitRoy described to him how the owner of a great plantation had called his slaves around him, and asked if they wished to be free: they all replied No, No. Darwin demanded of FitzRoy ("perhaps with a sneer") if the Captain thought the word of a slave in the presence of his master was worth anything. Affronted, FitzRoy ordered Darwin to leave his cabin, but shortly thereafter invited him back.