The September 11, 2001 terrorist attacks on New York City’s World Trade Center are referred to as “9/11.” However, Europeans read the day first, then the month. A joke is:
 
“Why do Americans make such a fuss about 9/11 anyway? What really happened on the ninth of November?”
 
“Did I miss something? What happened on the ninth of November?” was posted on the newsgroup uk.religion.christian on December 23, 2001.
     
         
Wikipedia: World Trade Center (1973-2001)
The World Trade Center was a large complex of seven buildings in Lower Manhattan, New York City, United States. It featured landmark twin towers, which opened on April 4, 1973, and were destroyed in the September 11 attacks, with 7 World Trade Center collapsing later that day due to the damage it suffered when the twin towers collapsed that morning. The other buildings in the complex were severely damaged by the collapse of the twin towers, and their ruins were eventually demolished.
   
At the time of their completion, the “Twin Towers” — the original 1 World Trade Center, at 1,368 feet (417 m); and 2 World Trade Center, at 1,362 feet (415 m) — were the tallest buildings in the world.
 
Google Groups: uk.religion.christian
More on New York - Bit long
Michael J Davis
12/23/01
Alec Brady

was inspired to say
>On 20 Dec 2001 12:30:57 -0800, .(JavaScript must be enabled to view this email address) (Paul Hardy)
>wrote:
>
>>Like everyone else, I’m
>>still trying to develop a coherent response to 9/11.
>
>Did I miss something? What happened on the ninth of November?
 
911 is the US dialling code for emergency services, since they use 9/11 for September 11th, it is reasonable to use the 9-11 abbreviation, without some irritating Brit. deliberately misunderstanding. But then I wouldn’t have expected you to, either.
   
28 July 2002, The Observer (London, UK), “The eleventh’s hour: The fallout of 9/11 is everywhere” by Vanessa Thorpe, Arts, pg. 7, col. 3:
So will the satirical response to 9/11 be left to the British comics—all feebly wondering, “What happened on the ninth of November anyway?”
 
12 September 2002, The Age (Melbourne, Australia), “Letters,” pg. 16:
It appears that an event that happened on the ninth of November is being celebrated by the media on the eleventh of September. Is that correct?
Lee Kennedy, Burwood
 
Twitter
Will
‏@Legoshoes
What’s all this about 9/11? Nothing special happened on the 9th of November…
6:24 PM - 10 Sep 2009
 
Twitter
The Personals Critic
‏@PersonalsCritic
wonders if Europeans think 9/11 happened on the 9th of November…
4:59 PM - 16 Sep 2009
 
7 September 2013, Taranaki Daily News (New Plymouth, New Zealand), “Ticklish trivia good for a laugh” pg. 7:
On Wednesday, it is the 12th anniversary of 9/11. With America’s flair for dyslexic-like dates being back-to-front from the civilised parts of the Western world, Mrs B, who is no great fan of the education system these days, suspects there will be a whole generation of young things growing up who think the attacks on America happened on the ninth of November.
 
Twitter
Seth Price
‏@squeethoven
Meanwhile, non-Americans be like, “9/11?  What happened on the 9th of November?”
9:23 AM - 11 Sep 2016
 
Twitter
Getting there!
‏@Dranalith
Americans remember 9/11 today, 2 months early. I don’t understand why, I can’t I find anything that happened on the 9th of November! X3
2:21 PM - 11 Sep 2016
 
Twitter 
Uncle Piss
‏@SalvaGraphics
i always thought that 9/11 happened the 9th of november but just now i realised that usa uses the m/d/y system
7:31 PM - 11 Sep 2016
 
Reddit—Jokes
Why do Americans make such a fuss about 9/11 anyway?
submitted February 15, 2017 by swiftobungee
What actually happened on the 9th of November?