The two ships of the HMS Beagle…

The two ships of the HMS Beagle expedition sail to the Río Negro in Argentina where Darwin leaves the Beagle for another journey inland with the gauchos.

On August 13, 1833, he meets former Argentinian president Juan Manuel de Rosas, who had left office the previous year, during one of the general’s several punitive expeditions against southern Argentina’s tribes of wandering horse-mounted indigenous peoples, and obtains a passport from him.

In The Voyage of the Beagle, Darwin describes him as a man of extraordinary character, a perfect horseman who conformed to the dress and habits of the Gauchos and "obtained an unbounded popularity in the Camp, and in consequence a despotic power.”

Darwin includes a story of how Rosas had himself put in the stocks for inadvertently breaking his own rule of not wearing knives on Sundays.

This appeals to his men's sense of egalitarianism and justice.