Let's be clear: the Pentagon should be congratulated. Thousands of female medics, drivers, and other servicewomen have already seen battle overseas. But they have often been blocked from key promotions because they lacked official "combat" designations.
They've also been held back by long-standing patterns of gender discrimination, including sexual harassment and assault. But removing the ban on female combat should help reduce those problems, too, by reminding men that women can be their equals in courage and determination.
Like the integration of African Americans and gays into the military, the new rules for female combat make an important symbolic statement about America itself. In ways that would have shocked previous generations, we have developed an impressive (if still imperfect) consensus about equality across race, gender, and even sexual orientation.
If only we could say the same thing about social class. Since the early 1970s, Americans have become less equal in income and education levels. That era also marked the end of conscription and the birth of the all-volunteer force (AVF). Ever since, our service men and women have come mostly from the less privileged sectors of our society.
Ironically, the AVF itself represented an effort to change that. In 1964, when 44 percent of American men held a white-collar job, just 20 percent of enlisted soldiers had a father who did. The following year, as America stepped up its war in Vietnam, only one-fifth of male soldiers had some education beyond high school; overall, for Americans aged 18 to 21, the fraction was almost one-half.
The big problem was the draft, which allowed student deferments favoring the well-to-do. So, two weeks before the 1968 presidential elections, Richard Nixon - that's right, Richard Nixon - proposed ending military conscription. Despite everything you might have heard, it wasn't long-haired radicals who brought the draft to a halt. It was free-market Republicans.
Listen to Nixon's 1968 speech, which was authored by the libertarian GOP economist Martin Anderson. Young Americans "recognize the draft as an infringement on their liberty," wrote Anderson, who would later serve as Ronald Reagan's chief domestic policy adviser. "To them, it represents a government insensitive to their rights."
After ascending to the White House, Nixon appointed Anderson and University of Chicago free-market scholar Milton Friedman to a commission for reforming the draft. The panel recommended an all-volunteer force, which "minimizes government interference with the freedom of the individual to determine his own life."
And it would be "her" military, not just "his." As its creators realized, the AVF would never reach its recruiting goals unless it also reached out to women. One 1972 Army advertisement focused on fashion, promising female enlistees "smart patent leather, low-heeled shoes, clutch handbag, and a matching umbrella and raincoat." But the same ad noted new vocational opportunities, too. "Almost every job open to men is now open to women," it declared.
The lone exceptions were combat jobs, of course. Still, women's enlistment in the military rose steadily, from 1.3 percent in 1971 to 7.6 percent in 1979. It has doubled since then, to about 15 percent. And we should expect it to keep climbing, now that women can truly occupy every position that is open to a man.
But the vast majority of those women - like their male counterparts - will continue to come from the middle and lower-middle rungs of our society. The poorest Americans generally lack the skills and qualifications to enter the military, while the wealthiest lack an economic incentive. That leaves the vast middle. In 2007, enlisted recruits had a mean household income of $54,768 - right around the national average.
And in tough economic times, the average doesn't go very far. According to the free-market myth, every social problem can be solved by expanding individual "choice." But some individuals have more choice than others. And the more they have, the less likely they are to choose the military.
In 1956, when conscription was still in effect, 400 of 750 graduating seniors at Princeton University entered the armed forces. Nearly a half-century later, in 2004, just nine did. And that was the highest number in the Ivy League.
My elder daughter attends an Ivy League school, too, and I wouldn't be surprised if her little sister does the same. But I would be surprised - and, I'll confess, distressed - if either of them joined the armed forces. They have so many other choices. Too bad that so many other girls don't.
Jonathan Zimmerman teaches history at New York University and lives in Narberth. He is the author of "Small Wonder: The Little Red Schoolhouse in History and Memory." E-mail him at firstname.lastname@example.org.