[The_Reader_David]

If you want to guess al Qaeda attack dates, ignore our holidays. Look at events in Muslim history, and I would guess for notable Muslim defeats. Sept. 11 was the anniversary of the relief column reaching Vienna during the last Turkish seige (which was broken the next day).

[John H K]

Look at events in Muslim history, and I would guess for notable Muslim defeats. Sept. 11 was the anniversary of the relief column reaching Vienna during the last Turkish seige (which was broken the next day).

I wouldn't bother worrying about "dates" at all. People are overly-fascinated with "significant" dates..I think it's because it sort of allows people to feel they have some control or can put some order to their fears.

You're REALLY stretching with the Turkish siege of Vienna business.

You can make ALL 365 days of the year "significant" if you're going to include everything that ever happened in Israeli history, every Muslim religious date of significance, and every day where something semi-important happened in the military history of Muslim states.

Weather was far too crucial to the 9/11 attacks for the date to have been vastly important; what was critical was clear skies from DC to Boston that day, and that it was a weekday with low passenger volume on the flights they chose to hijack.