Though horned helmets may not be historically accurate, Viking attire is required to participate in the festival.
Once the Viking ship lands on the muddy banks of the Ulla, the mock battle is on.
The sides clash during the mock battle.
Festival goers relive the battle on the muddy banks of the Ulla river.
The festival includes a replica of an 11th century Danish Viking ship made by young people in Catoria with help from National Museum of Roskilde and experts in Catoria's twin city, Frederikssund, Denmark.