The California gold rush of 1849 created fortunes for San Francisco merchants, whose wealth depended on control of the city's docks. But ownership of waterfront property was hotly contested. In an 1856 dispute over land titles, a county official shot an outspoken newspaperman, prompting a group of merchants to organize the San Francisco Committee of Vigilance. The committee, which met in secret, fed biased stories to the newspapers, depicting itself as a necessary substitute for incompetent law enforcement. But its actual purpose was quite different. In Dirty Deeds, historian...