When Bill Clinton was first elected president, one of the first items he tried to spend his political capital on was repealing the ban on gays and lesbians serving in the military. However, the opposition from conservatives was so strong that he had to compromise. The result was Don't Ask, Don't Tell.
Don't Ask, Don't Tell was a centrist policy at the time. It ended the earlier policy of actively ferreting out homosexuals in the military as a security threat. This was a liberal gain. But it stopped short of fully accepting homosexuality. This was a conservative gain.
In the years that followed, the sentiments of the country changed. Young people, in particular, accept gays and lesbians as normal Americans. This is true even of young people who are otherwise quite conservative. Just as important, a generation of military leaders came to power who also accepted gays and lesbians as normal members of the military. Their testimony, it seems, was the crucial step in convincing some Congressional Republicans to vote with the Democrats to repeal the law underlying Don't Ask, Don't Tell.
This story is the right way to make a controversial social change: take centrist steps until the change is no longer controversial to most people. Some people think this change should have been made long ago, that Don't Ask, Don't Tell was a sellout. Others think the change should not have been made at all, that homosexuality should not be normalized. But this day, when the Don't Ask, Don't Tell policy officially ended in the U.S. military, policy caught up with majority sentiment. Which is a good day for centrist social change.