"People all responded to the news of the war's outbreak much in line with the, by then, century-plus-old tradition of isolationism."
Sheet music for the anti-war song, "I Didn't Raise My Boy to Be a Soldier," sold 700,000 copies. The recording was number 1 for 13 weeks.
"He kept us out of war" was the campaign slogan largely credited with getting President Woodrow Wilson re-elected in 1916.
But just a few months later, after multiple provocations, Wilson asked Congress to go to war with Germany. On April 6, 1917, the declaration came -- and with it, a propaganda war, a battle for the hearts and minds of the American people.
"It's about the shift from saying that this is really not our war, to them being willing to put their shoulder to the wheel," said Matthew Naylor, head of the National World War I Museum in Kansas City, Mo.
"Modern public relations was very much formed by these early experiments in persuading people to a particular point of view or action," he said.
Demonizing the enemy was part of the message. But that raised the question: Who was the enemy? The loyalty of so-called "hyphenated-Americans" became an issue.
"We were a country, roughly, of 90 million people at this point," said Kennedy. "More than 30 million Americans at that time were either foreign-born or had at least one parent who was born abroad. And of those 30 million people, about a third of them -- 11, 12 million -- came from Austria-Hungary or Germany."
The U.S. had no army to speak of when war was declared. A draft was imposed. Enlistment was sold as an act of moral right.
"The Peacemaker" by Joyce Kilmer:
Upon his will he binds a radiant chain,
For Freedom's sake he is no longer free.
It is his task, the slave of Liberty,
With his own blood to wipe away a stain.
That pain may cease, he yields his flesh to pain.
To banish war, he must a warrior be.
"There are many of us who would not have made the choice that he did, but he was brave enough to do what he believed was right," said Miriam Kilmer, Joyce's granddaughter.
Even a hundred years later, Joyce Kilmer's story is troubling the way WWI is troubling.
We know him for this: "I think that I should never see a poem lovely as a tree." But he was a WWI poet.
Kilmer enlisted, leaving behind a wife and four small children. He wrote "The Peacemaker" in France, from the battlefield.
"That was a terrible thing, a terrible dilemma, a terrible choice that he had to make," said Miriam.
Joyce Kilmer was sent to the Western front, a line of trenches more than 400 miles long, from the Belgian coast to Switzerland.
Imagine: Both sides dug in, no-man's-land between them. The barbed wire, the filth, the stench. Nightmare gas attacks. And then, in 1916, the first tanks -- technology that modernized warfare but failed to end a three-year stalemate.
"There was a resignation in a sense," said Naylor. "If we all just sort of don't be firing at one another, we're all going to live longer. The United States entered the war, and things changed dramatically."