Colin Powell is above all a soldier. He loves his country and has dedicated his life to its service. His devotion to the U.S. Army is extraordinarily deep. Those qualities make him a fine man. They did not, however, make him a good secretary of state. Given the ideological proclivities of the Bush administration, perhaps Powell never had a chance. Perhaps no one should have had illusions about what he might accomplish.

The world took much reassurance from Powell's appointment. He was a moderate in a sea of hard-liners. He was a straight shooter. He believed in traditional diplomacy and international community building. His bona fides as a military man seemed to give him standing to challenge the Pentagon when that was necessary.

Powell came to the Army during Vietnam. He saw that conflict destroy the institution he loved, and he devoted two decades to rebuilding it, professionalizing it, putting the military back in charge of its own affairs, giving the professional officer corps a strong voice in how it was used. By the time of the Gulf War, the transformation was complete.

Nothing so exemplified it as Powell's doctrine: Go to war as a last resort; go with overwhelming force; go only with the unified support of the American people, and go with a clear strategy for consolidating the victory and leaving the battlefield. Iraq meets not a one of those criteria.

Who can ever forget Powell's dramatic presentation to the U.N. Security Council on Feb. 5, 2003, in which he made the case for going to war with Iraq? Few people trusted Donald Rumsfeld, Paul Wolfowitz, Dick Cheney and George W. Bush on Iraq. But here was Colin Powell, the wise head, saying we must do this, agreeing with that other wise head, Tony Blair. Those two could not be dismissed. But they were wrong, and they had reason to know they were wrong.

Powell put up the good fight, especially against Rumsfeld. But without support from Bush and Cheney, Powell's efforts were doomed. He was outgunned time and again. In retrospect, it's difficult to understand why Powell ever took the job. He had no relationship with Bush and held an entirely different worldview from the president and those close to him. Surely he could anticipate the battles he would need to fight, and surely he had to know he would lose most of them. Just as surely, those who banked on Powell's ability to sway events should have known they were willing themselves to hope for too much.

Powell did have his victories, too. He was personally responsible for preventing what seemed like almost inevitable war between India and Pakistan. He successfully pushed Bush to pay more attention to Africa, to AIDS and to other humanitarian issues. But on too many of the large issues -- North Korea, Iran, Iraq and especially on the need to pay heed to the views of other important nations -- Powell might as well have been talking to a rock.

Powell's leave-taking is emblematic of his tenure: The possibility of a breakthrough in the Palestinian question is palpable right now, and Powell wanted to stay on a few months to see if he could make some progress. Bush told him no.

So now Powell leaves the scene, to be replaced by Condoleezza Rice, a Bush loyalist. As national security adviser, Rice failed miserably at that job's central task: being the president's honest broker between Defense, State and the CIA to ensure Bush got the best advice. Her primary task at State apparently will be the same as Porter Goss' role at CIA: To strip the agency of those career professionals who had the guts to tell the White House things it didn't want to hear -- unpleasant truths that it needed to hear. Bush will hear no more dissenting voices. As in the campaign, there will be no admissions of mistakes. There will be no course corrections.

Powell tried to warn of that cliff ahead from the inside. He should have quit and gone public with his warning long, long ago.