This man was obviously a very large influence upon Darwin in that by requesting a campanion on his voyage to map the South American coast. Fitzroy was very aware of the previous captain´s difficulty with the loneliness of being in charge, and decided that it could all be avoid by the presence of intelligent conversation with another high-minded gentleman.
Fitzroy had actually planned on returning the Fuegians at his own expense after he had returned to England and lost his temporary Captainship of The Beagle. However, like Darwin he also had a kind uncle, The Duke of Grafton, who interceded on his behalf to the Admirality and his position as captaing of The Beagle was restored.
Darwin talks a little about Fitzroy and their quarrels in "The Voyage" but it turns out that it wasn´t just the close quarters and duration of time spent together that started their fights. Fitzroy was known for having quite a short fuse when it came to being questioned. In fact, the crew gave him the nickname "Hot Coffee" based on his voilent outbursts. One famous quarrel came when the two men broached the subject of slavery. When Darwin expressed discontent with the violent treatment of slaves Fitzroy told the story of a master who asked his slaves if they wanted to be free and they said no. Darwin asked how fair it could be for the master to ask this question and expect to receive an honest response. Fitzroy yelled that if Darwin could not trust the word of the captain they could not continue sharing a space and banished Darwin from his table. Later that night he gave Darwin a very thoughtful apology and invited him back.
Fitzroy also bought a schooner called the Adventure when they were in the Falkland Islands. Later, in Valparaiso when Darwin was exploring the Andes Fitzroy received a reprimand from the Admiralty for buying the schooner and took it so badly that he resigned as captain claiming doubts about his sanity. The crew managed to convince him otherwise, and when Darwin returned he was again captain and the voyage continued as planned. These events really show the character of Fitzroy, but despite his temper Darwin and Fitzroy got along reall well for a large majority of the 5-year journey.
Darwin´s voyage was completely at the mercy of Fitzroy and for it to be such a success speaks well of his influence upon Darwin. After the voyage Darwin and Fitzroy remained in contact and Fitzroy married a young woman to whom he had been engaged before the voyage. Darwin was very surprised because not once in the 5-year voyage had Fitzroy mentioned being engaged. They did have a few disagreements about religion after the voyage, when Fitzroy reaffirmed his belief in the literal account of the bible, saying that the shells in the mountains were proof of the Great Flood, and the Flora and Fauna of the world could not have taken such a long amount of time as the geologists would say because the grasses and herbs would have died in the long nights.
The five years that changed Darwin´s life forever were heavily influenced by the one man he spent most of his time with, and for this Fitzroy was a major influence upon the future publication of "The Voyage" and the "Origin of Species".