In June, the Washington Post celebrated the 40th anniversary of the biggest scoop in journalistic history — Watergate. Looking back on it, the Post has every right to crow. The story was so huge that every political scandal since has been labeled with the word “gate” tagged onto the end of it. However, the Post should also consider the adage, “You’re only as good as your last story,” because there’s a bigger one out there for the taking, if it only had the courage to pursue it. That story is, of course, the attack on the U.S. Consulate in Benghazi,...