From the introduction:
But not here. Yet.
Back East, the Civil War is in full swing, and the blood has already flowed freely on such fields as Manassas, Shiloh, and Fredericksburg. California has declared for the Union, but not all Californians are happy about it. Many of these so-called Copperheads keep their mouths shut and go about their business; others restrict themselves to arguing with acquaintances or publishing inflammatory broadsheets.
But a brave or desperate few look for more active ways to support the South. Perhaps the flow of gold and silver to Federal coffers can be diverted to the Confederacy; perhaps a loud blow for the South in California will raise morale back East and bring glory and opportunity to those who strike it. Or perhaps, just perhaps, sympathy for the Rebels can be harnessed into something much bigger, and a hefty chunk of California might be broken off for the Confederacy.