And so, on a day when Army Corporal Frank Buckles, the last American soldier to serve in World War I, was laid to rest at Arlington National Cemetery, the first American preview of War Horse, which takes place during the same conflict, was held at the Lincoln Center Theater's Vivian Beaumont. The synchronicity of this occurrence was not lost among cast members during the preview's after-party across the street from Lincoln Center at P.J. Clarke's clubby basement. But no one was fixating on history: the night itself had been too exciting, certainly judging by the highly enthusiastic reaction of a full house. 

"The adrenalin backstage was soaring this evening," said actor Joel Reuben Ganz, who, depending on the performance, portrays Topthorn, Coco, and John Greig. "We've been working hard for two months, some of us for a little longer than that. We were anxious to get in front of an audience." 

"You never know what you're going to get when there are strangers in front of you," said Elliot Villar, who is Allan and Soldat Klausen. "But I think everybody was pretty blown away by the intensity of the reaction tonight." 

Villar and other actors described the constantly in-motion feel of backstage throughout the performance. "You're never resting for a moment," Villar said. "There's always a sound guy adjusting your mike or a props person making sure about something else." This is not, in other words, a production in which actors are about to lounge in their dressing rooms dialing up golf on the Internet or besting their buddy's score on Angry Birds. 

Almost no one at P. J. Clarke's was spending much time watching golf or any other sport on the television above the bar; the need to unwind was as communally intense as the performance had been precisely wound. Like athletes, which they absolutely are, the War Horse actors tend to downplay the amount of exertion required of them; dwelling on it might edge into complaint, and no one wants to be typed as the kvetcher this early in the run. 

Occasionally signs of physicality, however, were revealed. Villar and David Pegram, whose roles include Joey as a foal and Private David Taylor, told me that adrenalin and exertion causes the actors to sweat pretty much straight through their woolen costumes. If that seems too intimate a detail for you, let me assure you that many audience members, by the performance's end, were equally sodden. Shedding tears - over tragedy, over reconciliation - tends to do that to you. 

Many decision makers crucial to the success of War Horse were in the audience last night, and some of the note takers among them - notes to be delivered during rehearsal the day after, not at a party where they would douse the mood -- were as joyful as the actors. "You're never quite prepared for the moment when there are a thousand or more people watching the thing you've been building for months," said Tom Morris, the co-director, with Marianne Elliott, of War Horse. "At the same time, you're grateful to have them there, because they provide you with so much information." 

For his part, Nicholas Hytner, the artistic director of London's National Theatre, where War Horse premiered in 2007 and which is co-producing the New York version with LCT, told me that he's looking forward to seeing just how the War Horse story resonates with American audiences. "The First World War doesn't loom quite so large for the Americans as it does for the British, who were in the conflict for longer. But the story is universally powerful." 

Brendan Lemon is the American theater critic for the Financial Times and the editor of lemonwade.com.