In a strange way, yesterday's resignation byAdm. William Fallon, chief of the U.S. Central Command, was an encouraging sign.

Not long ago, one of the Army's most respected field grade officers published a scholarly study of the origins of the Vietnam War. In "Dereliction of Duty," Col. H. R. McMaster indicted America's most senior military officers for failing to exert the leadership that might have saved us from a disastrous war. Since then, much of the officer corps has been waiting for the current crop of three and four stars to do the right thing.

The right thing is not to defy civilian authority. American officers swear to support the Constitution, which clearly subordinates the military authority to the political. McMaster argued that the right thing is to turn in your stars when you know the politicians are dead wrong.

We haven't seen much of that since "the Long War" began in 2001. Former Multinational Corps commander Lt. Gen. Ricardo Sanchez is now a critic of our five-year occupation of Iraq, but he was a true believer in 2003 and 2004, judging from his public pronouncements. Only after he was forced into retirement because of the Abu Ghraib scandal did Gen. Sanchez begin to air his dissent.

Then we have Army Gen. George Casey, who will go down in history as the William Westmoreland of Iraq. He was our top officer in Baghdad when I was there, relentlessly proclaiming success in the face of a growing civil war that he and a compliant intelligence chief refused to acknowledge. Like Westmoreland, Casey was rewarded with a promotion to chief of staff of the Army. No doubt he noted the fate of a predecessor, Hawai'i-born Eric Shinseki. Gen. Shinseki's career may well be the first casualty of the Iraq occupation, when he candidly admitted to Congress that it would take upwards of a quarter of a million troops to pacify the country.

The Bush defense establishment was not amused, and Shinseki was marginalized until his retirement (a ceremony that the Secretary of Defense could not be troubled to attend). Since then, the norm in the Pentagon has been sycophants like Air Force Gen. Richard Myers and Marine Gen. Peter Pace, who have been unabashed cheerleaders for the Bush administration.

Adm. "Fox" Fallon appears to be the first four-star to resign on principle. While his leadership and intellect will be sorely missed, his final act is the greatest service he has done for his country. It sends a message to the officer corps — particularly to disillusioned captains and majors who are leaving the Army in droves. His message is that integrity still counts.

This space does not permit a full examination of whether Fallon was correct to de-emphasize a military solution to the security challenges posed by Iran. I believe that he was, although no informed observer can deny that Iran's leaders are dangerous and unpredictable. Its nuclear program, its activities in Iraq, its aggressive naval actions in the Gulf, and its unreasoning bellicosity toward both Israel and the United States are all cause for concern. The question, however, is whether the same policy of arrogant threats that got us into an endless war in Iraq is the optimum solution to our challenges with Iran.

Adm. Fallon was unwilling to be the handmaiden of another ill-conceived war, and cashed in his stars to say so. No one will accuse him of dereliction of duty.

Retired Col. Thomas D. Farrell, a Honolulu resident, served as an Army intelligence officer in Iraq from June 2005 to May 2006. He wrote this commentary for The Advertiser.