In an 1876 speech at the dedication of an Abraham Lincoln statue in Washington, D.C., Frederick Douglass told the crowd, “Fellow citizens, the fourteenth day of April, 1865, of which this is the eleventh anniversary, is now and will ever remain a memorable day in the annals of this Republic.”

But how much do we really remember of that day, as its 150th anniversary nears? Do we remember that Lincoln’s assassination was part of a larger plan to kill Secretary of State William Seward (who was injured in a concurrent attack at his home) and Vice President Andrew Johnson (whose assigned attacker bailed and got drunk instead)?

Do we remember that when Lincoln was rushed to a house across the street from Ford’s Theatre, his gangly frame was so long he had to be laid diagonally in his impromptu deathbed? Do we remember that Mary Surratt, whose home was a haven for assassination conspirators, was the first woman executed by the U.S. government, when she and three others were hanged on July 7, 1865?

If we don’t, we learn it all in the astoundingly evocative new anthology, “President Lincoln Assassinated!! The Firsthand Story of the Murder, Manhunt, Trial and Mourning,” from the award-winning historian Harold Holzer. The first half of the book is a true crime story told through primary-source documents. We read Dr. Charles Leale’s account of rushing to the president’s aid after the shooting, examining his head, and “pass[ing] the little finger of my left hand through the perfectly smooth opening made by the ball.” The “$100,000 REWARD!” poster — perhaps the first wanted poster ever to include photographs, Holzer says — announces, “Let the stain of innocent blood be removed from the land by the arrest and punishment of the murderers.” A diary entry from John Wilkes Booth reads, “After being hunted like a dog through swamps, woods…with every man’s hand against me, I am here in despair.”

The second half of the book plunges readers into the sea of speeches, editorials, poems, sermons and other tributes that poured forth after Lincoln’s death, including that 1876 Douglass speech, a condolence letter from Queen Victoria to Mary Lincoln, and Walt Whitman’s immortal poem, “O Captain! My Captain!”

Taken together, these literary artifacts offer unrestricted access to what Holzer calls “the most infamous crime in American history.” We are sitting in the theater box when Lincoln is shot, standing by his side when he expires, and sharing the company of cultural luminaries (Ralph Waldo Emerson, Herman Melville, former President Franklin Pierce) and average citizens, alike, as they express their anguish over the country’s first presidential assassination.

Salon recently spoke with Holzer, who has published – count ‘em – 47 books on Lincoln and his times, and who is the recipient of the 2015 Gilder Lehrman Lincoln Prize. The conversation has been edited and condensed.

“The most infamous crime in U.S. history.”

I think so. There’s a lot of competition, I know. ...