In the spring of 1864, a student of medicine from upstate New York joined the Union army and ended up stationed in Virginia, across the Potomac River from Washington, D.C. Over the next year and a half, Richtmyer Hubbell, in his early twenties, visited Washington several times a month, witnessed some of the most compelling events of the Civil War period, and kept an account of them in his diary. His entries are unique for their time as well as for ours. They chronicle not the military aspects of the war but the political and social events and anticipate the impact that those events will have on the war and on the nation. In Potomac Diary we witness Hubbell's three meetings with Pres. Abraham Lincoln. We go with Hubbell to the Electoral College balloting in the 1864 presidential election, to Lincoln's second inauguration, and to the New Year's Eve ball at the White House in 1865. In the most eloquent entry, which is both chilling and prophetic, we share Hubbell's grief and insight into the assassination of Lincoln.