A former Secret Service agent on Friday recounted how a trip that former first lady Barbara Bush once took through New Jersey inspired his lifelong devotion to her.

Bush — the wife of one president and the mother of another — died Tuesday at her Houston home at the age of 92.

About 1,500 people are expected to attend the private funeral Saturday at St. Martin's Episcopal Church in Houston. First lady Melania Trump, former President Bill Clinton and his wife, Hillary, and former President Barack Obama and his wife, Michelle, are among those expected to attend.

A local reporter said on Twitter that Bush's Secret Service detail have refused to leave her coffin's side until she is buried.

It's the kind of loyalty that former Secret Service agent Jonathan Wackrow can understand. In a piece written for CNN, Wackrow recalls two moments with the former first lady that he considers "defining experiences in my career and testaments to her legacy, her candor and grace."

One of them happened after President George H.W. Bush had left office and he accompanied her to an appointment in New Jersey.

Wackrow said as her small, unassuming motorcade got into Jersey City from the Holland Tunnel, New Jersey state troopers greeted them "with full lights and sirens."

After her meeting, Bush insisted on stopping and thanking the officers who had warmly welcomed her to New Jersey.

"Peering out the limo's back windshield, I will never forget the image of Mrs. Bush shaking hands with the officers," Wackrow said. "It was a genuine moment of sincerity and unguarded kindness delivered out of the public eye, which, to me, defined this great woman."

On Wednesday, the New Jersey State Police remembered Bush by sharing a photo on their social media account.

Historian Jon Meacham said during Saturday's funeral that Barbara Bush is the "first lady of the greatest generation."

He said in his eulogy that she was "candid and comforting, steadfast and straightforward, honest and loving."

Meacham recalled her work bringing awareness to AIDS patients and in promoting literacy. He also spoke of her quick wit that made her so popular.

Meacham said she was devoted to her husband of 73 years, saying former President George H.W. Bush was the "only boy she ever kissed."

The Associated Press contributed to this report.

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