Michael Phillips 
Into the Long Dark Night (The Journals of Corrie Belle Hollister Book #6) 

The War Between the States has escalated into a full-scale conflict threatening to tear the nation apart. Having been invited by President Lincoln to come to Washington, D.C., to assist in his reelection campaign, Corrie finds herself a long way from home in a most unusual situation—a young woman from the Wild West, with little education and experience, in the seat of power at the nation’s capital. While writing and reporting from the battlefields, Corrie unwittingly uncovers a plot that could change the country’s course forever, but taking action will put her very life at risk.