Less than two weeks after delivering his second inaugural address, Abraham Lincoln wrote that he expected the speech to “wear as well as — perhaps better than — any thing I have produced.” But, he added, “I believe it is not immediately popular.” He was right on both counts. The speech, barely more than 700 words, is now considered one of the most important in American history. But on the day it was delivered, March 4, 1865, with the Union on the brink of victory in the Civil War, Lincoln had trouble placating his own party, much less his political opponents. And he opted to write words that addressed slavery in grand, religious terms, rather than itemizing the practical ways in which the country would have to begin moving forward. In “Every Drop of Blood,” Edward Achorn addresses sweeping issues about the war and the precarious state of the nation by narrowing his lens to the 24 hours around the inauguration and the many notable characters around the president that day. Below, Achorn discusses the hostility toward the president, the diaries of Southern women, how Stanley Kubrick is like Lincoln and more.

When did you first get the idea to write this book?

That’s a hard one because I suppose it was decades ago, when I first came across this speech. It has all this resonant language that sounds like something out of Shakespeare or the King James Bible. Here you have this president who’s been re-elected and virtually won a war that was a struggle for the country’s survival, and instead of celebrating he speculates on the war’s immense suffering. He says it may be God’s judgment for the sin of slavery. It’s not an ordinary speech. I’ve always thought I would want to write about it.

About five years ago, I decided to do it. A friend of mine said, “You should write about Booth and Lincoln on that day.” John Wilkes Booth, who murdered Lincoln six weeks later, was there watching the speech. But then I began to look at all the people who intersected with Lincoln that day. Walt Whitman was covering it. Clara Barton was trying to win Lincoln’s help for a project she was working on, to find out what happened to missing soldiers. You had Vice President Andrew Johnson, who was drunk at the ceremonies. Frederick Douglass, who was the most interesting to me.

What’s the most surprising thing you learned while writing it?

I’ve read all these books about how Lincoln was hated, but I was still surprised by how disdained and disliked he was by so many of his contemporaries. Liberal Republicans thought he was too calculating, too quick to weigh public opinion. Democrats thought he was a tyrant, a rube, and was destroying the Constitution. I think a lot of this was airbrushed out of history after he was assassinated, when he became a martyr. But when you go back to that day and look at what people were saying, you get a stunning sense of what Lincoln was up against. There’s a lot of hostility from all sides. I’m not sure how he withstood it. I guess he was defeated so many times in his life, had been down so many times, that he was able to take almost anything.