Tauranga Armoured Combat captain Charlie Tapsell said about 20 knights from New Zealand would compete against 15 to 17 Australians.
As well as the Tauranga and Waikato knights, B-Company from Auckland, Steel Thorns from Taranaki and a team from the lower North Island made up the Kiwi combat team, he said.
Mr Tapsell said knights battled toe-to-toe in the pro-fights, the mixed martial arts of medieval combat, with grapples, takedowns, and, of course, with weapons. Points were awarded for the number of solid hits a knight scored against his opponent.
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Mr Tapsell said the battles culminated in an amazing spectacle of four-on-four group fights where the last team standing wins.
The winning team at the end of the tournament takes home Australasia's most prestigious historical medieval battle prize: The Tattoo Cup.
Mr Tapsell said the full-contact combats took the more sedate medieval battle re-enactments to another level.
"It's a real spectacular event and a great spectator sport, and we hope to get up to 2000 people to come along to watch this Trans-Tasman battle for supremacy. All together the organisers expect about 10,000 people to come through the doors of the centre over the two days."