"John is a fighter," she said. "He earned his medals the old-fashioned way, by putting his life on the line for his country. No one will defend this nation more vigorously than he will — and he will always be first in the line of fire. But he also knows the importance of getting it right. For him, the names of too many friends inscribed in the cold stone of the Vietnam Memorial testify to the awful toll exacted by leaders who mistake stubbornness for strength."

Similarly, Kennedy, a sentimental favorite of the party, called the war in Iraq "misguided" and charged that the president had "squandered the enormous goodwill that flowed to America from across the world" after the terrorist attacks of Sept. 11, 2001.

In contrast, "John is a war hero who understands that America's strength comes from many sources, especially the power of our ideas," Kennedy said. "He knows that a true leader inspires hope and vanquishes fear. This administration does neither. Instead it brings fear."

In the convention keynote address, Obama described Kerry as a Vietnam War hero who has long made "tough choices when easier ones were available." At the same time, he faulted Bush's war policies, but without mentioning the president by name.

"When we send our young men and women into harm's way, we have a solemn obligation not to fudge the numbers or shade the truth about why they're going ... and to never ever go to war without enough troops to win the war, secure the peace and earn the respect of the world," the Illinois state senator said.

Kerry's former rivals for the party's 2004 presidential nomination also validated his credentials for the job of commander-in-chief.

"There is no one in these United States with more courage, more judgment, more resolve (than Kerry)...," said Dick Gephardt, the long-serving congressman from Missouri whose second campaign for president ended this year after the Iowa caucuses.

"John Kerry defended our freedom at the barrel of the gun. He put himself in personal peril to save the lives of his crewmates," added Gephardt.

Former Gov. Howard Dean of Vermont, who galvanized Democratic anger at Bush early in the presidential campaign, reiterated his populist message—"to be proud to call ourselves Democrats" in every part of the country and that "tonight, we're all here to represent the Democratic wing of the Democratic Party."

But Dean, too, returned to Kerry's war experience in an effort to underscore one of the key themes of the Democrats' four-day national convention—that their nominee will make American stronger in the face of terrorist threats.

"America's greatness rests on far more than the power of our arms," Dean said. "Our greatness is also measured by our goodness. It is in the capacity of our minds, the size of our hearts and the strength of our democracy."