UNITED NATIONS — Joseph Verner Reed, Jr., a U.N. undersecretary-general, former U.S. ambassador and chief of protocol under President George H.W. Bush, has died at the age of 78.

U.N. Secretary-General Ban Ki-moon announced Reed’s death on Friday, calling him “one-of-a-kind — a skilled diplomat, a global citizen, an art lover and a dear friend.”

Dana Marnane, spokeswoman for Greenwich Hospital in Connecticut, confirmed that Reed passed away at the hospital on Thursday. Fraser Seitel, a longtime friend and colleague, said he died suddenly.

Ban said Reed sent an email to several U.N. colleagues Thursday evening about further enhancing the U.N.’s appearance, which “may have been his last act: he was a champion of the United Nations to his very last breath.”

Reed served in the U.N. for 25 years under four secretary-generals, traveling the globe as an envoy. At the time of his death, he was an undersecretary-general and special adviser to Ban. According to the Greenwich Sentinel, his license plate read: USA-UN.

Reed was a descendant of Edward Doty, who came to America on the Mayflower. After graduating from Yale, he became private secretary to the head of the World Bank.

In 1963 he joined The Chase Manhattan Bank where he rose to be a vice president and assistant to Chairman David Rockefeller, who said he will miss Reed “more than words can express.”

“Joseph was a true ‘character’ in the very best sense of the word,” Rockefeller said in a statement. “He was a man of elegance, grace, wit, flamboyance and razor sharp intellect, a diplomat’s diplomat.

“As my closest associate for three decades at the Chase Bank, together we traveled the world, experienced unforgettable adventures and met thousands of people, from kings and presidents to hotel clerks and elevator operators,” Rockefeller said. “Joseph cherished and charmed every one of them.”

In 1981, Reed was appointed ambassador to Morocco by President Ronald Reagan and in January 1989 Bush chose him to be chief of protocol, which required him to plan and execute programs for foreign leaders visiting the president and accompany the president on official visits abroad.

Reed recalled in an interview last November with the Greenwich Sentinel his worst protocol gaffe: forgetting to ensure that Queen Elizabeth II had a step to stand on for her arrival ceremony at the White House in the spring of 1990. The result, he said, was that “all you could see was her hat bobbing up and down behind the microphones.”

It became known as “the Talking Hat” incident, which Reed called “a nightmare.”

But according to the paper, it created a bond between Reed and the diminutive monarch. Years later, when he attended a dinner on the royal yacht Britannia in Cyprus representing the U.N., Reed recalled that the queen suddenly pointed to him and said: “You should have the Talking Hat on your tombstone.”

Reed received awards from many governments, including France’s Legion of Honor.

His wife of 56 years, the former Marie “Mimi” Maude Byers, passed away last year. He is survived by two daughters, Serena Reed Kusserow of Anta Barbara, California, and Electra Reed of Greenwich, and four grandchildren.