When Leigh Ann Hester came home from Iraq she put grenade pins on her key ring. They were souvenirs of the Sunday morning in March 2005 when she and her Kentucky National Guard unit were tailing a supply convoy outside Baghdad. As many as 50 insurgents with submachine guns and rockets began to fire from an orchard and trenches along the road. The Americans pulled their Humvees over, and Sergeant Hester and S/Sgt. Timothy Nein crawled into one of the trenches. She shot a rifle while he lobbed grenades, then she threw while he fired. In 25 minutes the squad had killed 27 insurgents. Leigh Ann Hester, then age 23, was awarded the Silver Star for exceptional valor, the first woman ever to receive the honor for offensive action against the enemy.

Which is remarkable, considering the regulations designed to keep people like Sergeant Hester out of combat.

A recent report by the RAND Institute suggests the official policy on women in war zones is not "clearly understandable." That's an understatement. In Iraq, where the front line is everywhere, female soldiers are flying planes, policing the streets, working as gunners and medics. They're essential at checkpoints, since their male colleagues cannot comfortably search Iraqi women, and they're good at intelligence-gathering, which is the linchpin of the battle against terrorists. They've earned Bronze Stars and Air Medals. They've been buried at Arlington and West Point. They're in all the places where suicide bombers take aim and IEDs explode. But they're still curtailed by murky regulations that reflect a way of looking at warfare and the world that is outmoded, if not obsolete.

Nearly 15 percent of active-duty military personnel are female, so even before American capabilities were stretched thin in Iraq, most smart commanders understood that limiting the role of women would be disastrous. When the chair of the House Armed Services Committee wanted to tighten up combat regulations, it was the military brass, not women's groups, who seemed most discomfited. "I sit here in amazement that Congress would debate this issue when we've been doing it for so long," said the sergeant major who oversaw Hester's squad. The RAND report concluded that interviews with troops returning from Iraq found "a strict interpretation of the assignment policy could even prevent women from participating in Army operations in Iraq, which would preclude the Army from completing its mission."

Hester and Nein are a useful model of the kind of intergender teamwork most younger Americans experience, not just on the battlefield, but at work and at home. Because of that kind of progress the age of silly ephemera and mythology is past. We now know that women can manage to urinate in cups and go months without showers. We know that most men can work alongside them without going berserk out of either testosterone overload or innate chivalry so overpowering that they put themselves in harm's way. Is combat traumatic, terrifying, sometimes shattering? Yes, for women and men alike.

Twenty years ago, when Defense Secretary Casper Weinberger suggested that our sons were somehow more expendable than our daughters by saying, "I think women are too valuable to be in combat," conventional wisdom was that Americans would never stand for female soldiers' coming home in body bags. Someday soon the number of military women killed in Iraq will top 100, yet there's been precious little outrage. Opponents decry this as feminist social engineering. That hasn't been the case. While the progress the women's movement fomented helped lead to this moment, the last big boost came from market forces. At a time when the straitened military is making room for recruits with criminal records, a smart 23-year-old woman with drive and focus looks awfully good unless you're blinded by bias. "At the end of the day you need people who can perform," says Col. Cindy Jebb, who teaches at West Point. "It doesn't do the military any good to take folks who are qualified out of the fight."