The Ides of March is the 15th of March. The Ides of any month is the middle of the month. Ides is terminology that is Etruscan and southern European in origin from the 12th century BC. The Ides of March is also commonly known for its relation to the death of Julius Caesar.
The ides (or 15th) of March was a Roman holiday dedicated to the god Mars, and celebrated with a military parade. in 44 b.C., Julius Caesar was killed that day.