She revelled in the history-making campaign to break the males-only barrier to America’s highest office, declaring: "To all those who say we can't elect a woman president: we'll never know unless we try."
Victory was inevitable. Or so it seemed - until Iowa.
The startling victory of Barack Obama, the Illinois senator, in the first major contest was a severe blow to Clinton - and she never really recovered.
She had not paid much attention to Iowa, and only belatedly began to campaign intensively there.
Her strategy of emphasising her experience, in contrast with Obama's "change" message, backfired.
But Clinton fought back to win the New Hampshire primary, helped by a vulnerable moment when she became teary at a campaign event, showing a more human aspect of her steely personality.
"This is very personal for me," she faltered. "Some people think it's a game, who's up, who's down… it's about our country - it's about our kids' future."
But her mask of control seldom slipped again.
Clinton had prepared for a blow-out victory on Super Tuesday in February, when more that 20 states voted at once.
She did well, but Obama remained ahead in the delegate count.
|The two candidates have praised each|
other during a bitter campaign [AFP]
Unexpectedly, her husband, former president Bill Clinton, hurt her campaign more than he helped, with controversial comments that turned African American voters decisively against her. That lost her the South Carolina primary.
Without African-American support, her campaign was never the same.
Clinton's strategy called for her to wrap up the nomination by February.
In Maryland, Wisconsin, Virginia and a dozen other states big and small, Obama began building a lead in delegates that Clinton could never surmount.
Throughout a long, tough, gruelling campaign, the former first lady occasionally went on the attack against her opponent, with TV advertisements questioning his ability to handle major crises.
She also gave vent to frustration.
"So shame on you, Barack Obama," she declared in March.
"It's time for you to run a campaign that's consistent with your messages in public."
Even as it became clear she had slim hopes of securing the nomination she fought on tenaciously, ignoring some Democrats' fears her attacks on Obama were damaging the party's prospects to win back the White House.
And she succeeded to a remarkable extent, winning victories in Ohio, Texas, Pennsylvania, West Virginia and Kentucky.
She placed her hopes on white, working-class voters worried about the declining US economy.
She courted them in places like Bronko's bar and grill in Indiana, where she tossed back a shot of whiskey and a beer.
But she also embarrassed herself with a made-up story about coming under sniper fire on a trip to Bosnia.
Over five months and across dozens of state, Clinton and Obama fought each other as a nation watched, fascinated.
But Obama maintained a steady lead in delegates - the result of a superior political strategy.
When a Democratic party committee ruled against her over the votes of the disputed delegations from Michigan and Florida, the game was essentially over.
Still, Clinton's political career is not over.
She still has her senate seat and at age 60, she is considered young by American politics standards.
And should Obama lose to John McCain in the autumn, Hillary Clinton may well make another bid for the White House in 2012.