Waikato-Tainui is on Friday morning commemorating the 150th anniversary of the start of the Waikato Land Wars.
The iwi members have gathered at Mangatawhiri, near Mercer where government troops crossed the river into Waikato on 12 July in 1863.
The defeat of Waikato Maori saw them pushed into King Country and have nearly 500,000 hectares of their land confiscated.
Waikato Tainui spokesperson Rahui Papa said it had a long-term psychological effect on his people.
He said it has been a point of despair for the iwi, but has now become a catalyst of a regeneration of Waikato-Tainui and the Kingitanga movement.
Mr Papa said Waikato-Tainui had no option but to defend its territory from invasion.