On September 11th, 2001, planes hit the twin towers and the pentagon.
Event noteworthy that happened 12th of September was President George W. Bush declaring war on terrorism.
A noteworthy event that happened today in history on the 4th of September is that an avalanche destroyed the city of Plurs in Switzerland in 1618, killing 1500 people.
The bombings of the twin towers in New York happened on September 11th, but I don't know what happened September 9th.
None of great significance.
September 22nd in history, 1980 Iran is invaded by Iraq.
On September 17, 1943, Brjansk was captured by the Red Army.
the twin towers fall
On September 20, 1989, Puerto Rico was damaged by the Hurricane Hugo.
On September 7, 1981, The People's Court with Judge Wapner premiered.
You would use "last" if you wanted to say "last year", "last September" etc. If the event happened 2 September's ago, for example, you would use "on" to state the specific day. For example, "She died on September 3rd 2008".
On September 20, 1976, Playboy did an interview with Jimmy Carter about his lust for women.
There are tons of thing that have made history on September 1st. On September 1st of every year is Labor Day.