WASHINGTON — Barbara Bush, one of only two women in American history whose husband and son became president, died Tuesday. She crusaded for literacy and played a supporting role in former President George H.W. Bush's famed personal diplomacy that coincided with rapid-fire world change.

"My dear mother has passed on at age 92. Laura, Barbara, Jenna and I are sad, but our souls are settled because we know hers was," her son, former President George W. Bush, said in a prepared statement.

Barbara Bush and her husband, former President George H.W. Bush, attended the December 2008 Texas A&M University graduation ceremony in College Station, where their son, President George W. Bush, delivered the commencement address. (Agence France-Presse / 2008 File Photo)

Barbara Bush died at her Houston home on Tuesday, just two days after a family spokesman said she was refusing all further treatment. Earlier Tuesday, CBS News was told that she was alert and having conversations — and a bourbon — Monday night.

Her husband "is of course broken-hearted to lose his beloved Barbara, his wife of 73 years," said Jean Becker, George H.W. Bush's chief of staff. "He held her hand all day today and was at her side when she left this good earth."

Becker said that the 41st president is "stoic and strong, and is being lifted up by his large and supportive family."

After a public viewing on Friday at St. Martin's Episcopal Church in Houston, a private funeral service will be held on Saturday with about 1,500 people, expected to include several former presidents and first ladies. Her body will then be transported to College Station for a private burial ceremony at the George H.W. Bush Presidential Library. She will be buried beside her daughter, Pauline Robinson "Robin" Bush, who died of leukemia at the age of 3.

President Donald Trump -- who belittled her son Jeb Bush, and drove him from the 2016 presidential race -- remembered her as "an advocate of the American family" and of literacy. "She will be long remembered for her strong devotion to country and family, both of which she served unfailingly well."

Trump ordered that flags across the nation be flown at half-staff through the day of her burial.

Presidents of both parties celebrated her contributions to public life. Bill Clinton, who deprived George and Barbara Bush of another four years at the White House, joined with his first lady Hillary Clinton in calling her "a remarkable woman."

"She had grit and grace, brains and beauty. She was fierce and feisty in support of her family and friends, her country and her causes. She showed us what an honest, vibrant, full life looks like," they said.

"Barbara Bush was a fabulous First Lady and a woman unlike any other who brought levity, love and literacy to millions," George W. Bush said in his statement. "To us, she was so much more. Mom kept us on our toes and kept us laughing until the end. I'm a lucky man that Barbara Bush was my mother. Our family will miss her dearly, and we thank you all for your prayers and good wishes."

For him, she was mom. Other Americans came to know Barbara Bush as a formidable first lady who filled the White House with grandchildren and puppies, who spoke her mind and who knew how to generate publicity and money for causes she championed.

"She understood the symbolic power of being first lady," said Marlin Fitzwater, the former president's White House press secretary.

When organizations caring for AIDS patients lacked volunteers, she stopped by Grandma's House in Washington, D.C., where she held a baby with HIV and hugged an adult with AIDS. Her message: It's safe to touch and help those who have the disease.

When the 1991 Persian Gulf War stirred airline passenger security concerns, she left the U.S. Air Force Gulfstream on the tarmac and flew commercially to Indianapolis. Her message: I'm not afraid to fly and you shouldn't be, either.

When several Washington area malls banned the Salvation Army, she went shopping at a fashion center that allowed the bell ringers. She plunked a $10 bill in the red kettle. Her message: Don't mess with one of her favorite charities.

Former first lady Barbara Bush read "Arthur's New Puppy" during the Easter Egg Roll on the South Lawn of the White House in 2008. (Getty Images / 2008 File Photo)

"She used the power, she understood the power of that position, of that role — the visibility, the example set, the statement made by that," said Carl Sferrazza Anthony, a historian and author who has studied first ladies' roles.

Later, when her husband had lost the White House, she remained outspoken.

Asked in 2013 if she thought Jeb Bush, by then the former governor of Florida, should run for president, she replied: "I really don't....There are other people out there that are very qualified, and we've had enough Bushes."

The comment hobbled him somewhat, fueling concerns about a Bush dynasty. She later backed the effort with the full force of her personality, and on the stump, she could be formidable --though not enough to save Jeb Bush's campaign in 2016. She came off the bench for a last-ditch push in South Carolina, which turned out to be his last stand. She quipped that he was "one of my four favorite sons."

By then, Trump had poked the air out of "Low energy Jeb." And Trump had attacked her other son's presidency, taking issue with the oft-repeated claim that he'd kept America safe after the 9/11 attacks. "That's like saying the team scored 19 runs in the first inning, but after that we played well," he said at one point. "I don't think so."

She was no fan of Trump, and made no secret that she found his treatment of women appalling and his preparation for the White House badly lacking.

Popular, forceful

As first lady, she parlayed Americans' infatuation with the family's springer spaniels to benefit literacy, which she chose as her signature endeavor long before living in the White House. Being able to read and write, she felt, was key in preventing or solving other problems.

When her husband was vice president under President Ronald Reagan, she published C. Fred's Story written in the paw of the dog named for a Bush family friend from Houston. The sequel, Millie's Book, generated over $1 million for the Barbara Bush Foundation for Family Literacy.

Days before the 1988 presidential election, George H.W. Bush declined to predict victory, but he told an aide that if he won, the American people would fall in love with Barbara Bush. The polls indicated many did.

Barbara Bush, conscious of not over-exposing herself, remained popular even when his once high ratings plummeted.

"I think it was her reassuring presence. One hesitates to say grandmotherly aura, but there was something like that in the sense [that] here was a maternal figure whom everyone could identify with," said Lewis Gould, editor of American First Ladies 2001 and professor emeritus of the University of Texas-Austin.

Americans also found her refreshingly outspoken.

George W. Bush (center), born in 1946, was the first of George H. W. and Barbara Bush's six children. Their second child, Pauline Robinson "Robin" Bush (1949-1953), died of leukemia.

"Everyone always sensed that she was a lady with an enormous amount of spunk and opinions and a sharp eye for what was really going on," said Shirley Green, a Texan and longtime Bush aide. "Nothing got past Barbara Bush. I think people just knew and sensed that intuitively."

Despite the trademark faux pearls and public image, Bush could be a force to be reckoned with — dubbed "The Silver Fox" and known affectionately within the family as "The Enforcer."

"You know your staff is afraid of me," Sheila Tate, George H.W. Bush's 1988 campaign press secretary, quoted Bush as telling her husband.

He replied: "Good, keep it that way."

"She is a woman who helped her husband, but never lost a sense of herself," Tate said years later.

She had strong views on virtually every topic, including her husband's political opponents. More than once, that caused her difficulty.

The most striking example came during the 1984 presidential campaign in which, referring to Democratic vice presidential candidate Geraldine Ferraro, she made her infamous "rhymes with rich" remark. Bush said she was joking and thought the comment off the record, but she called Ferraro to apologize.

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She rarely deviated from offering "no comment" on matters of policy, saying she was not the one elected and that to do so would distract from the administration's work.

"A president has enough troubles — he does not need a wife to stir up more controversy for him," she wrote in her memoir.

Only after her husband left office did she confirm her support for abortion rights.

Despite maintaining radar silence in public, she often sat in on meetings at Camp David or in the residential quarters of the White House. She and others said she listened but did not chime in.

"She probably had a good deal more influence behind the scenes than she let people see," Gould said.

Fitzwater recalled walking in on discussions aboard Air Force One and observing that "she was giving the president an earful about something, and my guess is it wasn't the chocolate chip cookies."

Barbara Bush watches as her husband George H.W. Bush is inaugurated president of the United States on Jan. 20, 1989. Behind her, George W. Bush holds his daughter Jenna, 7, on his lap as she and her cousin Lauren Bush, 4, (on the lap of her father, Neil) have a disagreement. (David Woo / Staff Photographer)

Banter and practicality

As first lady, Bush worked to maintain some sense of normalcy and brought a devilish sense of humor to the White House.

She showed up at the annual Gridiron Dinner wearing a strawberry blonde wig — a retort to journalists who had written so much about her white hair.

She invited son Marvin to a state dinner, seated him next to actress Melanie Griffith and then dispatched a waiter with a handwritten note: "Dear Marvin, Please focus on the food. Love, Mom."

Her daughter-in-law, Laura Bush, told Larry King in 2003 that Bush is "who you want to sit by at a dinner party." She described her as natural, funny and entertaining.

During the White House years, she swam 72 laps a day year round in the outdoor pool and played tennis several times a week. In her '60s, she broke a leg while sledding with Arnold Schwarzeneger and her grandchildren at Camp David.

Throughout her adult life, she practiced what her husband called "a thousand points of light," volunteering in hospitals, hospices and nursing homes.

As first lady, she had her staff collect unused soaps and shampoos from their hotel rooms for homeless organizations.

Born to affluence, she retained a practical streak throughout her life even when the home address was the Waldorf Astoria in New York or 1600 Pennsylvania Ave. in Washington.

While her husband was in Congress, she took an auto mechanics course and later treasured a yellow toolbox gift, which she kept for decades and took to the White House. She wore Bill Blass and other designer clothes, but was crazy about Keds — so much so that her husband gave her 24 for a birthday.

Barbara Bush cringes as a low-flying jet ceremonially passes overhead during cake-cutting ceremonies for the Texas sesquicentennial held at Fair Park on March 2, 1986. At the time, her husband, standing behind her, was vice president. (Staff / 1986 File Photo)

The women of Wellesley

As with all first ladies, Barbara Bush had her critics — among them the women of Wellesley College.

In 1990, some 150 students signed a petition objecting to her selection as commencement speaker. They said she had dropped out of school to get married and gained recognition through her husband's achievements, while Wellesley taught them they would be rewarded for their own merit.

The first lady, who had invited Raisa Gorbachev to join her, went anyway. She told the graduates to believe in something larger than themselves, to make sure they had joy in their lives and to cherish their human connections.

"At the end of your life, you will never regret not having passed one more test, not winning one more verdict or not closing one more deal. You will regret time not spent with a husband, a friend, a child or a parent."

No matter how much the times change, she counseled: "Fathers and mothers, if you have children ... they must come first."

The Bush family poses for a photo in June 2015 at the family estate in Kennebunkport, Maine. The family gathered for a gala planned to celebrate Barbara Bush's 90th birthday. Among those present were former President George H.W. Bush, former President George W. Bush, former Florida Gov. Jeb Bush, and their families. (Evan Sisley / Office of George Bush)

From N.Y. to West Texas

Born in 1925 to Marvin and Pauline Pierce, she grew up in Rye, N.Y. Her father was president of the McCall Corp. At 16 she met "Poppy" Bush at a Christmas dance in Greenwich, Conn., and dropped out of Smith College in 1945 to marry the Navy aviator who had named his plane Barbara.

The Bushes soon moved to Connecticut, where he attended Yale University and played first base and Barbara kept score. In 1946, the first of their six children — George W. Bush — was born.

In 1948, the family of three took off for West Texas, where George H.W. Bush would first try his luck in the oil business and later in politics. In Odessa, they rented a two-room apartment and shared a bathroom with two women of "questionable occupations," Barbara Bush wrote in her autobiography. Two years later, they moved to Midland.

The wedding of George H.W. Bush and Barbara Pierce took place Jan. 6, 1945, in Rye, NY. (George Bush Presidential Library)

As young parents of three — Georgie, Jeb and Robin — they faced sudden tragedy when one day their 3-year-old daughter, woke up and said, "I don't know what to do this morning. I may go out and lie on the grass and watch the cars go by, or I might just stay in bed."

She died of leukemia before her fourth birthday.

In the mid-1950's, the Bushes left West Texas for Houston, where he concentrated on the offshore oil business. The family, now complete, included Neil, Marvin and Doro.

When George H.W. Bush unsuccessfully ran for the U.S. Senate in 1964, Barbara Bush began what turned out to be decades of campaigning for her husband, needlepointing her way around Texas to calm campaign jitters.

Friends and associates say the decades in public life when her husband was a congressman, U.S. ambassador to the United Nations, chairman of the Republican National Committee, U.S. liaison to China and director of the CIA helped prepare her for the White House.

The Bush years came at a time of remarkable transformation — the Iron Curtain parted, the Soviet Union dissolved and Saddam Hussein invaded Kuwait, leading to the first Gulf war.

She spent considerable time globetrotting with the president and entertaining world leaders in Washington, Camp David or at the family's oceanside home in Kennebunkport, Maine.

"She'll be remembered for more than just the White House and being first lady," Fitzwater said.

Before, during and after the White House years, the Bushes practiced informal diplomacy. Prime ministers and presidents and Saudi princes came to Kennebunkport. They entertained Soviet president Mikhail Gorbachev at Camp David, where he pitched horseshoes and took Queen Elizabeth II to Camden Yards, where she watched an Orioles game.

First lady Barbara Bush and Russian first lady Naina Yeltsin played with children during a visit to the children's program at Martha's Table in June 1992. Martha's Table is a non-profit organization that serves homeless and hungry people in Washington,D.C. (The Associated Press / 1992 FIle Photo)

Return to Houston

After her husband's 1992 defeat, the couple returned to Houston — spending half the year there and the other half in Kennebunkport. She resumed driving — a station wagon in Houston and a convertible in Kennebunkport.

She became a lucrative draw on the speaking circuit. She wrote two books, Barbara Bush: A Memoir and Reflections: Life After the White House.

And she lived to see two sons elected governor, George of Texas and Jeb of Florida' and to witness her eldest sworn in as president — something Abigail Adams, the only other woman whose husband and son were president, did not live to see.

Presidential scholars say Barbara Bush's influence in shaping the second President Bush should not be underestimated. "She is unique because she was a first lady and the mother of a president. I think some of her image may be affected, however, by her son's presidency and how his place in history turns out," Gould said.

They shared self-assuredness, quick tempers and quick tongues.

Barbara Bush playfully slaps her son George during a photo op at the family home in Kennebunkport, Maine, in June 1999. George W. Bush, standing with his wife, Laura, was Texas governor at the time. (1999 File Photo)

"My mother and I are the quippers in the family, sharp-tongued and irreverent. I love her dearly, and she and I delight in provoking each other, a clash of quick wits and ready comebacks," her eldest son wrote in A Charge to Keep. "Occasionally, our comebacks are too quick, too ready."

At a literacy event in Dallas in 2003 after the publication of her last book, she commented on the latter.

"I've been amused by comments about the book, or rather its author," Bush mused, noting that one adjective that kept popping up in articles and reviews was "tart."

"Not a tart," she quipped, "Just tart."

In addition to her husband, Bush is survived by five children and their spouses, 17 grandchildren, seven great-grandchildren; and her brother, Scott Pierce. Preceding her in death, in addition to her daughter, were her siblings Martha Rafferty and James R. Pierce.

Kathy Lewis is former deputy chief of the Washington Bureau for The Dallas Morning News.