This will eventually be cleared up in trial.
I also posted an article (snippet) above where the military clarifys that it happened on the 12th.
March 11 is no typo.
In AD utem #9, SOI2 says it happened on the evening of 3/11.
In AD item #11, SOI3 says they were drinking on the 11th.
In AD item #12, SOI5 says an iraqi national approached him on 3/11 to inform him of the incident.