A lot of Colin Powell's work as secretary of State involved maintaining and repairing America's friendships, which were under constant strain from the Rumsfeld Pentagon and the administration's unilateralists.
One of his last unpleasant chores was a 24-hour trip to Beijing last month to reassure the Chinese government that the United States was not supporting independence for Taiwan, no matter what the Pentagon might be saying.
But, in the end, what left Mr. Powell bitter and frustrated, as he was described by some close to him, was Iraq - the war he thought shouldn't have been fought without America's traditional allies. And, most especially the assignment he had been given to purvey a lie to the United Nations Security Council about weapons of mass destruction.
It was like Powell, having enlisted for a four-year hitch, to serve out that hitch ... and then to resign without much discussion with President Bush, who must have known it would be futile to ask him to stay. "Casualty of War" was the way Powell's position was described last June by Wil Hylton, who had interviewed him at great length for an article in Gentleman's Quarterly magazine. But frustration over Iraq was not all there was. Since President Johnson first brought Powell into the White House as an intern, he had played a basically nonpartisan role. He could have run for office - even for president - and maybe won. But he remained the soldier, serving country, not party.
The first to be named to the Bush cabinet in 2001, Powell found he had joined an intensely partisan administration that did not leave much room for nonpartisan service. It is hard to guess when Powell decided to quit, but it was not recently. Powell said he had never planned to stay longer than one term. One of the reasons he stayed was to get the administration to focus on the atrocities in Sudan.
But serving as secretary of State, on the whole, was clearly not a happy experience for Powell. He once reminded me in conversation that we shared origins in the South Bronx, and an education at New York's City College. "And what did we learn there?" he asked me. "We learned that you always go for the main chance." For Secretary Powell, his main chance was no longer in the Bush administration - if it ever was.
• Daniel Schorr is the senior news analyst at National Public Radio.