Of all the senior foreign-policy officials during the tumultuous George W. Bush presidency, Condoleezza Rice was the least complicated. The others — Colin Powell, Dick Cheney, Donald Rumsfeld — had at one time or another imagined themselves as a potential president, been captains of industry or the military and were experienced in the dark arts of bureaucratic Washington.

Rice, intelligent, poised and always gracious, was cut from a different cloth and — especially in the early years as Bush’s national security adviser — appeared overshadowed and outmatched by her more famous counterparts. Yet, she rarely seemed publicly perturbed and never looked back, only forward, preternaturally optimistic that things would work out in the end.

Now, in her memoir, “No Higher Honor,” Rice looks back, offering unexpected candor about her tenure as national security adviser in Bush’s first term and as secretary of state. For a longtime Rice watcher — as diplomatic correspondent for The Washington Post from 2002 to 2010, I traveled on many of the overseas trips she describes — the moments of self-doubt and regrets that she describes are a revelation.

(Full disclosure: In 2007, I wrote a book that critically examined Rice’s diplomacy — too critically in the view of some of her aides. Rice never complained to me personally, but in press interviews she rejected a central premise: that the mistakes she had made as national security adviser had hamstrung her options as the nation’s chief diplomat. In her memoir, she makes one brief, but positive, mention of me.)

In many ways, this is the first serious memoir of the Bush presidency. It is long — more than 750 pages — and dispenses with the obligatory autobiographical material because Rice wrote that in last year’s “Extraordinary, Ordinary People.” Thus it is a comprehensive look at the foreign policy strategy carved out by the president and his aides, but without the usual score-setting typical of such tomes. And although Rice defends many key decisions, most especially the choice to invade Iraq, she also acknowledges the mistakes and missteps made along the way.

‘No Higher Honor: A Memoir of My Years in Washington,’ by Condoleezza Rice. (Crown. 766 pp. $35) (AP/Crown Publishers)

In public, Rice was such an articulate and fierce defender of Bush administration policies that it is striking to learn that she realized the errors were piling up. I interviewed her a year after the Sept. 11, 2001, attacks to understand why U.S. alliances were so frayed, and she insisted, even privately, that there were absolutely no problems. Now, in her book, she admits that the administration mishandled concerns about the Kyoto climate change treaty — “a self-inflicted wound that could have been avoided” — and failed to respond positively, after the Sept. 11 attacks, to NATO’s invocation of the article that it was considered an attack on all NATO states.

Rice emphasizes that the well-publicized disputes with Cheney and Rumsfeld were (in her mind) not personal, but simply business — policy differences over consequential issues. Given how roughly Cheney and Rumsfeld treated her in their accounts of the Bush years, such equanimity is remarkable.

Although Rice writes in workmanlike prose, her book comes alive when she recounts the confusion and panic in the days and weeks after the Sept. 11 attacks. No matter what one thinks about the policy decisions that were made — and many would be criticized afterward — one cannot help but feel sympathy for administration officials as they grapple to find their way forward, both professionally and personally. A particularly heart-stopping moment was when, for 24 hours, the entire White House staff believed they had been exposed to a deadly toxin for which there was no reliable antidote.

Less satisfactory is Rice’s account of the decision to invade Iraq. She never really explains how it came about, except in her telling the move against Iraq began as coercive diplomacy that eventually achieved unstoppable momentum. She recalls the president asked for military options in December 2001, three months after the Sept. 11 attacks, and then told advisers in September 2002 that either Saddam Hussein would give up his weapons or there would be war.

But were there discussions about the pros and cons of an invasion? Was there a policy process that allowed all points of views to be exposed? Rice does not say. That was her responsibility as national security adviser, and it is a failing of the book that she does not address the many questions about her management of the national security process in the first term.

She hints at the problems, saying, “I’ve asked myself many times how I might have broken this cycle of distrust and dysfunction.” She recounts being constantly surprised by backdoor maneuvers by the vice president’s office, including one that led her to threaten to resign. She admits to failing to press the Pentagon hard enough for a post-invasion plan and regrets her handling of intelligence concerning illicit weapons in Iraq. The intelligence turned out to be wrong, casting a pall over the motivations for invading Iraq.

Rice is much more open detailing the administration’s struggle to deal with Iraq’s descent into violence during Bush’s second term. She congratulates herself on forcing more State Department officials into the field, but she might want to read “We Meant Well”— a hilarious and often depressing account by a foreign service officer of what really happened on the ground.

Although Rice offers sharp and sometimes penetrating portraits of foreign leaders, her portrayal of Bush is largely blank. This is strange because there has never been a president so close to his national security adviser — or his secretary of state, which gave her extraordinary access, power and influence in the second term.

The president constantly pops up in the narrative, usually with a quip and an insight that Rice finds to be significant. But she never really explains what drew her to him and how they became such a close team. “I liked him,” Rice writes. “He was funny and irreverent but serious about policy.”

There are moments of insight, such as irritation at Bush’s tendency to undermine his staff. Rice also writes that she “visibly stiffened” when Bush said he had gotten a sense of Vladimir Putin’s soul, after hearing a “rather syrupy story” about a cross the Russian leader’s mother had given him, lending the “perception that the President had naively trusted Putin.”

As is usual in administration memoirs, there are sections of historical revisionism. Rice dwells at length on Bush’s decision to call for a Palestine state in 2001, giving it great significance, but wonders why it wasn’t well noticed at the time. Perhaps that’s because President Bill Clinton had already done so before he left office.

In addition, Rice’s account of a fierce debate over whether to remove North Korea from the list of state sponsors of terror is missing a key detail — that intelligence analysts had discovered traces of highly enriched uranium on documents provided by the North Koreans. But she does admit she persuaded Bush to take a gamble that backfired spectacularly.

Reading Rice’s book, one is struck by the irony that she spends her final months grappling with North Korea and trying to forge peace in the Middle East — two issues where Bush had broken most decisively with the approach taken by Clinton. And yet, eight years later, Rice and Bush had come full circle, trying to find a solution along the lines taken by the Clinton administration.

Rice makes a credible case that the Israelis and Palestinians were closer to a final peace deal than is generally known. Yet, in the unfortunate practice of American politics, the incoming Obama administration upended the Bush administration’s policies toward the Israeli-Palestinian conflict. After they took office, Obama administration officials spoke scornfully of Rice’s peace efforts — and now have so bungled the process that the two sides are even further apart.

Rice’s memoir is a reminder that the foreign-policy choices facing the United States are complex and difficult, with no easy solutions. A little less hubris at the beginning of an administration, with less of a desire to break with the past, might make the future less rocky. Rice has acquitted herself well in telling her side of the story; now she awaits the judgment of history.

Kessler, who writes The Fact Checker column for The Washington Post, is the author of “The Confidante: Condoleezza Rice and the Creation of the Bush Legacy.”