What event is celebrated on 13th July in Northern Ireland
Which country celebrates 23rd April as it's special day
Which northern city celebrated its 1900 anniversary in 1971
I don't know about the 13th July, but the 12th July is the anniversary of the Battle of the Boyne and is the big day for Orange Order marches in Northern Ireland (and in some parts of Scotland) .
13th July is the day of the Scarva sham fight in Northern Ireland. There's a re enactment of the Battle of the Boyne where William of Orange defeated the forces of King James.