When gold was discovered in the foothills of the Sierra Nevada in 1848, it seemed as if most of the world rushed in to California – which, until then had been a sparsely-settled outpost of Mexico, dreaming the decades away. The climate was enchantingly mild, Mediterranean – warm enough for groves of olive trees and citrus to thrive, and the old missions crumbled away as if nothing had or would ever change. The old, proud Californio families with names like Verdugo, Vasquez, Pico and Vallejo kept vast cattle herds and lived in extensive but rather Spartan-plain estates. There were a few handfuls of American settlers who had come overland, or by sea; they tended to what little trade there was, and an energetic and slightly shady Swiss entrepreneur named Johann Sutter had a vast agricultural and establishment centered around a fortified holding in present-day Sacramento. It was on his property, and in the course of building a saw-mill that gold was discovered. And change came upon the enchanted land – and the place called Yerba Buena turned almost overnight from a hamlet of eight hundred souls on the shore of San Francisco Bay into a ramshackle metropolis of 25,000 and more in the space of two years.