‘I never before came across a man whom I could fancy being a Napoleon or a Nelson…His ascendancy over everybody is quite curious: the extent to which every officer and man feels the slightest praise or rebuke would have been before seeing him incomprehensible.’ Thus wrote the 22-year-old Charles Darwin of Robert Fitzroy, the 26-year-old captain of the Beagle, a good but not unusual example of captains during the Royal Navy’s zenith in the decades following Trafalgar.