Pennsic is the largest SCA event in the world held every August in Pennsylvania (Kingdom of Aethelmarc),USA. It is the traditional war between the East Kingdom and the Middle Kingdom. Supposedly the loser gets Pittsburgh (Barony of the Debatable Lands). The full name is the Pennsic Wars. This year will be the 35th running of the event that started out in a field in Ohio, and now consumes the resources of a small western Pennsylvania town for 3 weekends and the 2 weeks in between.
Last year the official attendance was slightly over 13000 gentles from all corners of the Known World. Pennsic is a definite "must get to one day" for the hardened SCAer. It's an amazing experience, with literally hundreds of collegia, days on end of tourney and war fighting, shopping that will send your credit card screeching for cover and thousands of other SCAdians to meet.