One of the many heroes in the repeal of “don’t ask don’t tell” (DADT) has resigned. Jeh Johnson, the general counsel at the department of defense, will return to the private sector at the end of the month.

Johnson is one of those impressive people for whom public service is a form of thrill-seeking. His current stint at the Pentagon is his third tour away from private law practice in New York City. He was an Assistant United States Attorney in New York (1988 to 1991) and he was the general counsel of the Air Force (1998 to 2000).

Johnson has been at defense since the beginning of President Obama’s term. He’s had to deal with myriad complicated and controversial issues, from the prison at Guantanamo Bay and military tribunals to the growing use of drones. Conducting and co-writing (with Army Gen. Carter F. Ham) the study on the impact of allowing gay men and lesbians to serve openly in the military was no less complicated or controversial. But the nine-month effort in 2010, which was greeted with suspicion initially by gay groups as a dodge by the president to avoid action, gave Congress the ammunition it needed to repeal the discriminatory 18-year-old law.

Part of what he did was survey the men and women of the armed forces. While 70 percent overall said repeal of DADT wouldn’t be a big deal, 60 percent of the Marines begged to differ. Making a comparison to similar squeamishness over integrating the armed forces in the 1940s. “The lesson to be drawn from that,” he told the New York Times,  “is that very often the predictions about what is going to happen overestimate the negative consequences and underestimate the military’s ability to adapt.”

And adapt the military did.

We’ve seen gay military members kiss their partners upon their return home from deployment. Just this month we saw the first same-sex wedding at the storied chapel at the U.S. Military Academy at West Point.  And the sky hasn’t fallen as a result.The U.S. military is still the greatest fighting force the world has ever seen. Allowing gay men and lesbians to serve openly — to serve the country they love and be true to themselves — made the U.S. military stronger and our country safer. That they can do so ought to be Johnson’s greatest legacy at the Pentagon.