Who is General Rosas from The Voyage of the Beagle and what is their importance?

General Rosas is a popular military leader whom Darwin meets while in Patagonia. Rosas and Darwin get along famously, with the General inviting the naturalist to his camp and table. Rosas also helps Darwin by allowing him to accompany troops on the march through dangerous territory. A deadly war goes on between the European settlers and the wild natives.