In 1990, as America's first lady, Barbara Bush delivered a Commencement Address at the prestigious Wellesley women's college in Massachusetts that experts later voted one of the 50 best political speeches in history.

It came at an historic moment. The Cold War was all but over. The wife of Soviet leader Mikhail Gorbachev, Raisa, was among the assembled guests. Barbara Bush's husband was the leader of the free world, and the world seemed to be becoming freer every day.

Mrs Bush urged the graduating students to follow their own dreams, not those imposed on them by society.

If Barbara Pierce had been born after 1925, it's possible that instead of being the wife of one president and the mother of another, she could have been president herself.

"Who knows, maybe somewhere out in this audience there may even be someone who one day will follow in my footsteps and preside over the White House as the President's spouse. And I wish him well."

If Barbara Pierce had been born after 1925, it's possible that instead of being the wife of one president and the mother of another, she could have been president herself.

The most electorally successful of the Bush dynasty, George W, is said to be the most like his feisty mother, while George Senior and Jeb are "too nice".

Barb was very effective as a surrogate discussing policies from economics to foreign affairs during her husband's many political campaigns.

Although in an interview with CNN's Larry King in 2010 she admitted, "I wasn't courageous enough to run, and I'm still not courageous enough to run".

Whether it was courage, her personality, or the expectations of her gender and her time that kept her in a supporting role, Barbara Bush was very much the power behind the throne.

Tough as nails, adding steel to the spine of a capable and likeable husband who was good at glad-handing, but could come across as kind of a wimp.

With her snowy white hair and triple strand of fake pearls, Barbara Bush may have looked like a grandmother, but behind the scenes she could talk like a bartender. And while she kept her silence on issues where she disagreed with her husband, like the right to choose to have an abortion, saying "I wasn't president", on other subjects she would speak her mind.

Barb was no wimp. Asked what she thought of the first female candidate for the vice presidency, Democrat Geraldine Ferraro, after a debate with George, Barb said, "I can't say it, but it rhymes with 'rich'".

With her snowy white hair and triple strand of fake pearls, Barbara Bush may have looked like a grandmother, but behind the scenes she could talk like a bartender. And while she kept her silence on issues where she disagreed with her husband, like the right to choose to have an abortion, saying "I wasn't president", on other subjects she would speak her mind.

As first lady she was photographed holding babies with HIV at a time when many Americans still believed you could catch AIDS on contact.

Mrs Bush chose literacy as her mission in the White House, where previous presidential spouses like Lady Bird Johnson had championed the beautification of highways with flowers, or simplistic drug policies like Nancy Reagan's "Just Say No".

Both President and Mrs Bush were devastated by his re-election defeat in 1992 to Bill Clinton, yet later formed an unlikely, almost parental bond.

"I think he (Clinton) thinks of George a little bit as the father he didn't have, and he's very loving to him. I love Bill Clinton, maybe not his politics, but I love Bill Clinton," Mrs Bush said.

The couple's eldest son George W was elected to replace Mr Clinton in the White House in 2000, but when their second son Jeb was looking at running in 2016, Barb wasn't convinced.

She said America had had enough of the Bushes and the Clintons: "I would hope that someone else would run, there's no doubt in my mind that Jeb is best qualified to be president, but I hope he won't run."

But when Jeb did run, Barb was back on the campaign trail in her 91st year, and as her son's campaign faltered, she unleashed a broadside against the eventual nominee Donald Trump:

"It is slightly shocking to me ... He sort of makes faces and says insulting things. I mean he's said some terrible things about women, terrible things about the military. I don't understand why people are for him. I'm a woman, I'm not crazy about what he says about women ... I'm sick of him."

Barbara and George Sr voted for Hillary Clinton, and they missed Mr Trump's inauguration, saying mischievously their doctors had warned them it might kill them.

The sweethearts who exchanged daily love letters as George flew combat missions as a navy pilot against Japan, and rushed to the altar in 1945, stayed together for a remarkable 73 years until Barbara's death.

More than half a century after they married, George had written to her again:

"You give me joy that few men know, I have climbed perhaps the highest mountain in the world but even that cannot hold a candle to being Barbara's husband."

In that famous Wellesley address, Barbara Bush had told students, "At the end of your life you will never regret not having passed one more test, winning one more verdict or not closing one more deal. You will regret time not spent with a husband, a child, a friend or a parent."

By her own measure, Barbara Bush should have had few regrets.