The 15th of March (tomorrow) was once known as 'The Ides' in Roman times and came from the Latin word 'idus' meaning 'half division' which indicated that it was half way through the month. It was the festival day of the Roman God of War, Mars and a military parade was usually held in his honour.
Its more sinister connotations derive from the fact that Julius Caesar was assasinated on the 15 March in 44 BC, by a group of Roman senators who stabbed him 23 times. A seer had predicted his death as being on the 15th March, hence the term in Shakespeare's play, 'Beware the Ides of March'. Here's hoping that the 15th will be a peaceful day for all.