For a while, I didn't know that that the 2012 U.S. consulate bombing in Libya was on September 11 :/.
Honestly, it really seems that they did it then to make the U.S. angry. Throwing the evangelical conservatives into a fit of rage about how the Muslims did it on that day as some sort of cocked-up ritual because they're "so radical". All it really is is a mind game that we're ever-so-naively falling for.
Also, so many people are confused about what was bombed. I'm doing a presentation on the relations between the United States and Libya, and it was the consulate in Benghazi that was bombed. The U.S. embassy, if I recall, is in Tripoli.