Reasons for war
War between tribal groups occurred for both practical and cultural reasons. Practical causes included population pressure, competition for land – particularly horticultural land, competition for natural resources and the need to protect stored food supplies. Cultural reasons were linked to the concepts of mana and utu. Tribal groups might seek to fight others to increase tribal or personal mana. Additionally, utu might require a group to make reprisals for insult, injury or trespass. A well-known saying about warfare states, 'He wāhine, he whenua, e ngaro ai te tangata' (Through women and land do men die).
Rise and distribution of pā
Pā seem to have first appeared in New Zealand around the 1500s. There are thousands of pā around New Zealand. The fact that 98% of pā are located in horticultural areas suited to Polynesian crops suggests that there was a relationship between horticulture and war. It was common for pā to have areas for storage of the harvest.
Mana and utu
Traditionally the mana or prestige of a tribe and its members was all important. Tribes and their rangatira could increase mana by triumphing over other tribal groups. Insults, slander, theft, murder, assault and adultery by other tribal groups could negatively affect mana. To restore the tribal mana it was often believed necessary to seek utu. A common translation of utu is revenge; however, culturally it refers to returning balance. Any reason for waging war on another tribe was known as a ‘take’.
At the conclusion of a war, it was vital to make peace. Women often had a role in sealing the peace. Arranged marriages between victors and high-ranking women of defeated tribes was common. Ngāti Porou elder Tuta Nihoniho spoke about the importance of women and peacemaking:
[K]i te houia e te tane te rongo o te whawhai, e kore e mau, ka kiia tera he rongo tama-tane, he atua, he taitahae. Engari ka riro ma te wahine e hohou te rongo, ka kiia tera he rongo tama-wahine, ka mau te rongo, he rongo taketake.
If a peace is concluded in time of war by men, it will not be a firm or lasting one. It is termed a male peace, and stands for treachery, deceit, trouble. But if women assume the function of making peace, that is known as a female peace, and it will be a firm, durable one.
A peace arrangement known as a tatau pounamu (greenstone door) was a metaphorical reference to an enduring peace. The door represented safe passage between the territories of two tribal groups. Pounamu referred to the enduring nature of the peace, and in some cases a pounamu weapon would be handed over to signify the peace.
A saying suggested that this, and peace made by women, were the two enduring types of peace. ‘He whakahohou rongo wahine, he tatau pounamu’ (a peace secured by a woman is as lasting as a peace from tatau pounamu.)
Peace on Rēkohu
The Moriori people of Rēkohu (Chatham Islands) were able to forge a continuous period of peace. According to Moriori tradition, after a series of wars an important chief, Nunuku-whenua of the Hamata tribe, declared an end to war, putting a permanent restriction on murder and cannibalism. ‘From now and forever, never again let there be war as this day has seen!’ This became known as Nunuku’s law. It is likely that the ability to hold to Nunuku's law was assisted by the wealth of food resources on the Chatham Islands.