Nireaha Tāmaki was born at Te Pākawau on the Manawatū River probably between 1835 and 1837. His father was Matiu Tāmaki, a descendant of high rank of Rangitāne and Hāmua; Nireaha was sometimes known as Nireaha Matiu. His mother, Maraea Te Hungatai, also known as Reikura, was a woman of rank descended from both Kahungunu and Rangitāne. Nireaha's principal hapū were Hāmua and Ngāti Mutuahi, and he was also kin to Ngāti Kapakapa, Ngāti Te Wānanga, Ngāti Matangiuru and Ngāti Māwhai.
As a small child Nireaha was brought up for a time by Reihana Tākawa, who gave him the name Te Mōrehu. When he was older the Rangitāne chief of Puehutai on the upper Manawatū River, Te Hirawanu Kaimokopuna, took an interest in him, ensuring that he learnt about the mana of his ancestors. When Te Hirawanu died Nireaha was regarded as his heir, with responsibilities towards his many hapū. The elders arranged Nireaha's marriage to a high-ranking woman of Hāmua and Muaūpoko; this was Rihipeti. Their children were Matewai and Pirihira. Nireaha had several other marriages or liaisons and a large family. At different times in his life he lived at Palmerston North, Tahoraiti (near Dannevirke), Masterton, Ngawapūrua (near Woodville) and Te Hāwera (Hāmua).
Nireaha Tāmaki began his life's work as the protector of his people's land interests in 1871, despite being initially disadvantaged by his relative youth and junior rank. He participated in the sale of the so-called Forty Mile Bush (the Wairarapa end of the Seventy Mile Bush), but aimed to retain substantial reserves for his various hapū at Pāhiatua, Ngāwapūrua, Te Hāwera and Tūtaekara. In spite of being among the sellers of the 62,000-acre Mangatainoka or Manawatū–Wairarapa No 3 block in Forty Mile Bush in 1873, Nireaha retained interests in several of its subdivisions and reserves, and after a lifetime of land dealings he still owned an estimated 5,000 acres.
In the 1870s Nireaha began a series of court battles with the western chiefs of Rangitāne; he was often allied with Huru Te Hiaro of Te Hāwera, nephew of Te Hirawanu Kaimokopuna. In 1872 his claim to be registered as a grantee of the Mangatainoka No 2A or Tūtaekara block was dismissed. In 1875 he tried again to have his name inserted as a grantee, saying that he had not agreed to Hoani Meihana Te Rangiotū's allocation of subdivisions of the block to various hapū. His application was denied by the court. Later, he applied on behalf of himself and his party for a separate grant of the southern portion of the block, since his cultivations and the burial places of his ancestors were there. Te Rangiotū and Te Peeti Te Aweawe objected, and again the application was denied.
After the estimated 66,390 acres of Mangatainoka had passed through the court, the Crown offered to purchase the land. For a whole day Nireaha, on behalf of Ngāti Mutuahi, disputed rights to the block with Te Rangiotū, who was forced to postpone negotiations to sell. In June 1875 Nireaha wrote to Donald McLean, then native minister, demanding a rehearing of his claim. He wrote again in July, threatening to resort to arms if a rehearing was not granted. McLean seems to have succeeded in resolving the issue at a meeting with Nireaha shortly afterwards.
Nireaha was amenable to European settlement despite his battles to retain land. Europeans knew him by the nickname 'Bulls-tail'. With Huru Te Hiaro he ran the ferry over the Manawatū River east of the gorge. In August 1877 he reached an agreement with the Crown that permitted the river to be bridged, and in recognition of his services he was paid a subsidy of £25 per annum. In 1885 he was painted by Gottfried Lindauer, dressed in a thrummed cloak, carrying a mere, with a huia feather in his hair.
By the early 1880s Nireaha's fights were against the government. After it put a pre-emptive restriction on the Mangatainoka blocks for the purposes of railway construction, in January 1884 Nireaha wrote demanding that the restriction be removed, and that compensation be paid for his improvements. He wanted the government to provide three stations for the Forty Mile Bush area, called Hāwera, Pāhiatua and Ngāwapūrua.
Government land purchase agents did all they could to buy individual grantees' shares of the various Mangatainoka blocks, disregarding the wish of the chiefs to retain them as a tribal estate. By January 1884 the government had succeeded in purchasing 41,430 acres. The principal chiefs, including Nireaha, insisted that further substantial reserves be made, amounting to five or six per cent of the total, or between 3,000 and 4,000 acres.
In January 1885 Nireaha was visited by Hōri Rōpiha, who had returned from a visit to England determined to convince the Hawke's Bay and Wairarapa Māori to cease land selling and to boycott the Native Land Court. As a counter-measure to Rōpiha's influence the government's agent, Thomas McDonnell, attempted to bribe the non-sellers of the Mangatainoka block, including Nireaha, with a higher price per acre.
In April 1885 the government, wishing to sell the portion of its share of the block not needed for the railway, called the case before the Native Land Court. Nireaha's withdrawal from the court forced it to adjourn to Ōtaki in late May. In May 1887 Nireaha still retained his shares in Tūtaekara, and was making matters difficult for Waata Tohu and other land sellers. In March 1888 he wrote to the minister for native affairs, Edwin Mitchelson, complaining about errors in the surveyor's plan of Te Hāwera, and asking for a rehearing. He was in danger of losing all his cultivations and improvements to the Crown, and the survey line had been approved in the Land Court during his absence at a funeral.
In 1890 Nireaha succeeded in getting the Crown proclamation removed from his various blocks so that he could lease them. But his victory was tempered by the Crown's demand that the owners pay for the survey. Nireaha pointed out that the surveys, hearings and purchases were all government initiatives. The Crown's agents decided that it was only fair that non-sellers should pay costs on the land they retained: they thought that some European prospective purchaser was trying to avoid paying the costs of survey, and were reluctant to believe that Nireaha genuinely wanted to retain his land.
Nireaha's difficulties with the Crown and its surveys reached their height in 1893 over the Mangatainoka subdivisions. No survey had been made at the time of the original grants, thus invalidating the grantees' certificate of title. The frequently cited legal case, Nireaha Tāmaki v. Baker, was heard before the Court of Appeal in 1894. Nireaha claimed an area of 5,184 acres, either as part of the block granted to himself and others in September 1871, or, if that title was invalid, as land which had never passed the Native Land Court, and was therefore held under customary Māori title.
The court decided that Nireaha's title, if any, was based on customary tenure, and that by a precedent set in 1877 in Wī Parata v. The bishop of Wellington & the attorney-general, the Crown's transactions with Māori for land held under customary tenure were acts of state, and could not be reviewed by any court, including the Court of Appeal. Moreover, there did not exist any body of customary law known as 'the Ancient Custom and Usage of the Māori People' even though that phrase had been used in the Native Rights Act 1865. Nireaha was ordered to pay the costs of the hearing.
Nireaha's defeat was discussed in the Kotahitanga newspaper, Huia Tangata Kotahi. It was claimed that the Court of Appeal had refused to make a decision in his case because if it did, other sales to the government could be questioned on the same grounds. The attention of Māori was focused on Nireaha, especially after he decided to appeal to the Privy Council. The appeal was heard in May 1900, and judgement handed down in May 1901. The decision was reversed, the Court of Appeal being adjudged to have jurisdiction over the question of whether the land in dispute had been ceded to the Crown. The respondent, Surveyor General John Holland Baker, was ordered to pay the costs of the 1894 hearing.
In the long run, Nireaha's victory established several important principles which affected many subsequent cases: the courts would take cognisance of Māori custom, although no customary right could be enforced until confirmed by statute; Māori customary title was not inconsistent with the fact that the fee simple of the whole territory of New Zealand was vested in the Crown; and, most importantly, a system of customary Māori land tenure did exist and should be recognised in court decisions. In response to the Privy Council's decision, the government passed legislation which limited Māori rights to scrutinise the Crown's land-purchasing procedure through the courts. Nevertheless, the theoretical considerations at least remained on record, and this in itself made the decision of lasting importance.
Nireaha's success in land matters ensured him a position in Māori leadership. He had played a minor role in the early years of the Kotahitanga movement, and a more prominent one later at the parliament held at Pāpāwai, and in the Māori councils. He became advisory counsellor of the Rongokako Māori Council in 1906. In the early 1900s he built a meeting house, Te Poari, at Hāmua for its meetings. He was a haka leader in Ngāti Kahungunu performances at Rotorua during the welcome to the duke and duchess of Cornwall and of York in 1901. The same year, he accompanied Tamahau Mahupuku to the Sydney pageant celebrating the inauguration of the Commonwealth of Australia. Nireaha succeeded in getting the name Hāmua given to the post office at Te Hāwera, which effectively changed the town's name and commemorated his major hapū. The township of Nireaha, first established in 1886 on land he had sold, was called after him. In 1907 he was elected a member of the Kōmiti o Tūpai of the Tāne-nui-a-rangi committee, responsible for the collection and vetting of Rangitāne and Ngāti Kahungunu genealogy and tradition.
Nireaha had been an Anglican in early life, but became a convert to Catholicism in the 1890s. In 1896 he donated land at Hāmua for a hall, and later gave more for a church. He died on 3 July 1911 at Hāmua. When the day for his burial arrived, he was carried from his house, Te Mihi-ki-a-te-Kuini, to the cemetery. The Catholic bishop of Wellington performed the ceremonies and the sermon was preached by an Anglican minister, Hekiera Te Raro. The funeral was attended by 3,000 Māori and Pākehā. A monument in his memory was erected by his daughters, Meri Ngawhiro and Pirihira Tātere.