Three white students are trying to reverse the rules which civil rights campaigners established decades ago by claiming that they were denied university places because of their colour.

Their lawyers were confident of a fair wind when they arrived in court, since President George Bush had already shown his sympathy for the students' argument. But they had reckoned without the Iraq effect.

Of the thousands of pages of documents placed before them on Tuesday, the judges focused on just 30: statements by prominent retired officers and politicians, including three joint chiefs of staff, two former defence secretaries and several four-star generals.

Best known among them was Norman Schwarzkopf, who led the US forces during the previous Gulf war. Though not known for his liberal views, Gen Schwarzkopf is just one of the many who have lent their names in support of the University of Michigan's race-conscious admissions policy.

Michigan and its law school give extra points to minority applicants for admission, contending that a diverse student body is a worthy goal that benefits all students.

The plaintiffs, backed by the Centre for Individual Rights, argue that this amounts to denying them places because they are white.

But the benefits of the policy have have long been recog nised by the US forces, who see it as essential for national defence.

"Today there is no race-neutral alternative that will fulfil the military's and the nation's compelling need for a diverse officer corps of the highest quality to serve the country," the military brief said.

The plaintiffs' lawyers were completely wrong-footed. The day that US troops made their most significant advance on Baghdad was not the best on which to take on the military establishment.

Before the solicitor general, Theodore Olson, finished the first sentence of his argument on the White House's behalf against the University of Michigan policy, Justice John Paul Stevens interrupted him, demanding his opinion on the military leaders' brief.

"The timing was remarkable," said Carter Phillips, the Washington lawyer who wrote the brief.

"The context of us being at war, in a multicultural environment, with a whole series of concerns about diversity. I don't think you can discount Norman Schwarzkopf."

Hours earlier the civil rights leader Jesse Jackson was on the court steps rousing black and Hispanic student protesters with the words: "There are more blacks in prison than in college. Young America, fight back."

To get the Rev Mr Jackson and Gen Schwarzkopf on the same side, not to mention the alma maters of every supreme court judge and several Fortune 500 companies - including Microsoft, American Express, BP and Coca-Cola - is testimony to Michigan's success in pulling together a coalition of interests to support its case.

But military leaders' submission attracted the judge's attention not only because of the timing but because, whatever its record abroad, the US armed forces are regarded as the most successful illustration of affirmative action there is.

The army was racially integrated by the time of the Korean War, while Martin Luther King was still in college and segregation was still legal. But although recruitment improved, promotion was rare for black soldiers, and the consequences were divisive.

To improve their representation in the higher ranks the military academies of West Point, Annapolis and Colorado Springs use race as a factor in admissions.

In 1962 only 1.6% of the army officers were black; today the figure is 8.8%. Given that African-Americans comprise 21% of military personnel, a substantial gap exists.

There is no evidence that standards have fallen. The military academies are generally thought more academically prestigious now than 30 years ago.

The court is expected to rule on the case in June.