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9/11, 3/11, 12/11What's with all the terrorist attacks on the 11th?

By Michelle Tsai
Posted Monday, Dec. 17, 2007, at 6:48 PM ET
12/11 Bombing in Algiers. Click image to expand.

Last week, the North African branch of al-Qaida claimed responsibility for the Dec. 11 truck bomb attacks at the United Nations offices in Algiers. Al-Qaida has carried out other terrorist attacks on the 11th: Sept. 11, 2001, in the United States and March 11, 2003, in Madrid, Spain. Does the 11th day of the month hold special meaning for jihadists?

Probably only as a reminder of the Sept. 11 attacks. The number 11 doesn't have significance in Islam, but even if it did, it wouldn't explain why attacks take place on those dates. That's because the pattern exists only in the Gregorian calendar. The Muslim calendar, which is based on the cycles of the moon, has 12 months but contains about 11 fewer days per year than the solar calendar. That means our dates don't correspond at all to lunar dates.

In the lunar calendar, the attacks on the Twin Towers took place on the 22nd day of the sixth month, Jumada al-thani, in the year 1422. The Madrid bombings occurred on the 19th day of the first month in the year 1425, and the recent suicide bombs in Algiers exploded on the first day of the 12th month of 1428.* The group that claimed responsibility for the truck bombs in Algeria gave two explanations for the timing of the attack—to commemorate a key operative who had been killed and to precede the Muslim Feast of Sacrifice—but neither involved the number 11.

Other numbers do have special significance in Islam. For instance, the number five represents the prophet Mohammed, his daughter Fatima, her husband Ali, and their two sons. Shiite Muslims, however, are far more likely to be influenced by numerology than the fundamentalist Sunnis who make up al-Qaida.

Experts believe that terrorist attacks are sometimes timed to coincide with the anniversaries of events, often in the near past, that are significant to the terrorist organization. This lends political power to the prior act and builds support among followers. For instance, a group may plan a revenge bombing on the anniversary of the assassination of a beloved leader.

But in general, terrorist groups have little incentive to schedule a big plot for the 11th, or for any day in particular. If you're focused on carrying out an attack, sticking to a specific date will make the plan less flexible and potentially make the culprits easier to catch.

Got a question about today's news? Ask the Explainer.

Explainer thanks Reza Aslan, author of No god but God: The Origins, Evolution, and Future of Islam; Mahmoud Ayoub of Temple University; Mark Juergensmeyer of University of California at Santa Barbara; and James Lewis of the Center for Strategic and International Studies. Explainer also thanks reader Brian Zumhagen for asking the question.

Correction, Dec. 27: The story originally misstated the sixth month in the Islamic calendar as Rabi' al-thani rather than Jumada al-thani. The article also included the wrong Islamic date for the Algiers explosions: The bombings took place on the first day of the 12th month in 1428, not the 12th day of the first month. (Return to the corrected sentence.)

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Michelle Tsai is a writer living in Jersey City, N.J.
Photograph of Algiers bombing site by Fayez Nureldine/AFP/Getty Images.
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