After 11 Months, The Haverford School Unveils a New Leader

The Haverford School’s previous head of school, John Nagl, hands his reign over to award-winning educator Tyler Casertano.

Culminating with commencement last month, John Nagl concluded a progressive eight-year tour of duty as head of school at one of the Main Line’s most revered private institutions. A retired Army officer and veteran of both Iraq wars, Nagl finished out the academic year at the Haverford School, staying on so as not to leave administrators and students in a lurch.

Tyler Casertano begins his tenure as Haverford’s new head of school on July 1. The former assistant head of school for advancement and strategy at St. Albans School in Washington, D.C., Casertano taught U.S. and ancient history courses, served as a class adviser and coached lacrosse. He’s received St. Albans’ Hall-Hoffman Award, given annually to an exemplary teacher-coach, and has twice received the University of Chicago’s Excellence in Teaching Award.

The son of educators, Casertano grew up on boarding school campuses and is a Yale University alum. He holds a master’s degree in private school leadership from Columbia University’s Teachers College.

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Just before classes began, it was announced that 2020–21 would be Nagl’s last year at the all-boys school, after his personal and public personas clashed ahead of a heated presidential election. It came in the form of an open letter he co-authored with retired U.S. Army Lt. Col. Paul Yingling, posted Aug. 11, 2020, on

Addressed to Gen. Mark A. Milley, chairman of the Joint Chiefs of Staff, the letter criticized Donald Trump and his presidency. It suggested that an impending loss on Election Day could result in a troublesome transition of power, implying that Milley might have to direct U.S. military forces to intervene.

The Haverford School
Photo by Jon Krause

Among other things, the letter labeled Trump “a lawless president” and compared him to Julius Caesar in “assembling a private army capable of thwarting not only the will of the electorate but also the capacities of ordinary law enforcement.” It also accurately predicted “street protests” and a swelling of Trump’s “private army.”

The Haverford School community reacted. In the This Is Lower Merion and Narberth online newspaper, one parent and alum said, “Great day for the Haverford School! I commend the board of trustees for forcing John Nagl to resign. He has been an embarrassment!”

The parents contacted for this story wouldn’t be interviewed. Alumni Association president Jack Kirkpatrick, parent of a 2020 graduate, agreed to one but later backed out.

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Just the school’s ninth headmaster since 1884, Nagl abruptly resigned on Aug. 24 with a joint letter penned with newly named board chair Maurice Glavin. He and the school both maintain that it was his decision to resign. A 1983 alum and father of three recent graduates, Glavin says the board wouldn’t have asked Nagl to leave. “John was getting restless,” he says. “He saw the nation, saw what was going on, then reflected on his expertise, training and strategy from his national security days, and found it difficult to do the nation right and also be head of school.”

Nagl publicly apologized “not for what I said, but for fact that I said it,” he admits now. “It was political and shouldn’t have been. Heads of school should represent the whole flock. I violated that code. The job as head of school isn’t to publish divisive articles, no matter how strongly you feel about an issue or how compelled you feel to say it. It did damage to my day job.”

The controversy over his letter to Milley wasn’t the only thing that factored into Nagl’s resignation. During the pandemic, Nagl reflected on the fate of his father, a Navy man and nuclear power engineer, who died at 56. Nagl, 55, became conscious of his own remaining time and “itches to scratch.”

In 20 years of Army service, where he became a lieutenant colonel and earned a Bronze Star Medal, Nagl led a tank platoon in Operation Desert Storm and served as the operations officer of a tank battalion task force in Operation Iraqi Freedom. He’ll return to the national security world, though he hadn’t announced where at press time. In publishing the piece on, he noted that he missed his involvement in the national discussion. “I feel an obligation to be part of that world, and that’s very hard to do as an independent head of school,” he says.

The replacement process at the Haverford School began immediately this past September. A search committee chaired by alum Bart Smith retained Boston’s Carney Sandoe & Associates, widely regarded as the leader in independent head of school searches. They even convinced its president, Devereaux McClatchey, to lead the search. In-person and survey responses from 750 participants resulted in unified constituencies and a position description. Then the marketing began. “Most of the [independent school] ecosystem was aware of [the opening],” says Smith. “John enjoyed pulling the oars through to the end of the race, and he’s been incredibly focused on our boys during these difficult months.”

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Nagl’s time at the Haverford School ushered in a new era of distance and remote learning, ahead of COVID. The “2020-25 Strategic Plan: Lifelong Leading and Learning” finalized a campus master plan with the addition of the new middle school building, which opened last fall. Nagl also led the “Character at Our Core” campaign, which surpassed its $50 million goal. “Without question, the Haverford School is in a better position than it was eight years ago,” says Smith, a parent of two lower school boys.

Nagl is also proud of less-promoted enhancements that “changed the culture of the institution.” In response to dealing with a drug and alcohol scandal his first year, he initiated the “My Brother’s Keeper” anonymous reporting protocol. He also believes he’s made the school more equitable and inclusive. “I felt, and feel, very confident that one of the things taught in the Army is to improve your battlefield position, and I’m leaving the Haverford School better than I found it,” he says. “I moved the ball down the field.”

“The job as head of school isn’t to publish divisive articles, no matter how strongly you feel about an issue or how compelled you feel to say it. It did damage to my day job.” —John Nagl, Outgoing Haverford Head of School

But it was often in the face of personal setbacks. In 2016, Nagl was arrested after allegedly assaulting his son with a chokehold during an altercation over marijuana and a restricted cell phone. His son called Haverford Township police, who filed a report and charges. Nagl was released on $30,000 unsecured bail.

But it’s hard to keep a smart man down. Nagl’s a guy who can “move the needle nationally,” says Glavin. And he always knew that, with Nagl’s intellect and talents, a departure was imminent. “It’s bittersweet. We’re friends, but my entrepreneurial background tells me we need to look at opportunities to get better.”

An Omaha, Neb. native, and the oldest of six, Nagl was a distinguished graduate of the United States Military Academy Class of 1988. He earned his master’s and doctoral degrees in philosophy from Oxford University. Before coming to Haverford in 2013, he was the inaugural Minerva Research Professor at the U.S. Naval Academy. He’s taught at West Point and Georgetown University.

Beyond academics, Nagl is a member of the Council on Foreign Relations and a Senior Fellow Senior at the Foreign Policy Research Institute in Philadelphia. He was the president of the Center for a New American Security in Washington, D.C., and remains a non-resident senior fellow. He served on the Defense Policy and Reserve Forces Policy boards and testified before the Senate Foreign Relations Committee.

Nagl also authored Knife Fights: A Memoir of Modern War and Learning to Eat Soup with a Knife, and he was on the writing team that produced the Counterinsurgency Field Manual. “I feel fortunate to have contributed on the battlefield, literally, and in the battlefield of ideas—and I’ve missed that,” Nagl says.

And there must be a lesson for students, especially at a school whose motto proclaims that it’s “preparing boys for life.”

“Discretion is the better part of valor,” says Nagl, who ardently believes in freedom of speech and press and in teaching kids to ask good, hard questions. “One can say all sorts of things, but the freedom to say it doesn’t mean one should say it if it conflicts with your responsibilities.”

Even so, Nagl will be no silent listener in moving forward. “No, it appears it will continue,” Nagl says of his tendency to express himself. “It’s a chronic condition.”

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