Taiwhanga, the son of Tawatawa and his wife, Wahi, was a direct descendant of Tama-ki-te-ra. His hapu was Ngati Tautahi of Te Uri-o-Hua section of Nga Puhi at Kaikohe. His first wife was Mata (Martha) Rawa, of Te Arawa, and they had seven children, three dying in infancy. His second wife was Mary and they had at least one child.
As one of Hongi Hika's warriors Taiwhanga participated in the first Nga Puhi expedition to the Bay of Plenty in 1818. Sections of this war party continued down the East Coast as far as Tapatahi, Tokomaru Bay, where they forced the defenders of the hill-top pa to capitulate by setting fire to the palisades. Seven years later Taiwhanga was again with Hongi's forces at the battle of Te Ika-a-ranga-nui, on the Kaiwaka River, near Mangawhai. There he is said to have executed a skilful rescue of Nga Puhi leader Moka at the height of the engagement. The forces harried defeated Ngati Whatua as far as Rotorua, where Taiwhanga took captive a woman of Te Arawa, after killing her husband and two children. The woman, Mata Rawa, became his wife and shared his work. She died in August 1837, probably from the breast cancer which a visiting surgeon had operated on in 1834.
Taiwhanga's life reveals some of the changes affecting Maori society in the 1820s and 1830s. He was fascinated by the foreign crops, animals and methods of agriculture which he observed being introduced at the Kerikeri mission station. He began work there as a foreman for John Butler in 1821. Butler paid him an axe a month and relied on him as his main overseer of field and garden. According to Butler, Taiwhanga was 'a man of quick discernment'. He rapidly became efficient in breaking in the land, burning off and laying out for planting. His skills in reaping, mowing and threshing encouraged other Maori to gain similar experience.
Between 1822 and 1824 Taiwhanga spent nearly 18 months with Samuel Marsden, the chaplain of New South Wales, at Parramatta, expanding his knowledge of European farming methods and skilled trades. He appears to have known the CMS missionary George Clarke, a gunsmith, with whom he returned to New Zealand in March 1824, on the French frigate Coquille. At Kerikeri he now worked briefly with another missionary, Richard Davis. After a last battle expedition in 1825 he abandoned fighting to work as a sawyer at the Paihia mission. Meantime his garden was evidence of his horticultural skills. By the end of 1826 it was producing potatoes, corn, cucumbers, pumpkins, melons, onions, shallots, peas and parsnips. Vines and peach trees were flourishing, and he had an acre in wheat. His wife took in washing for ships' officers and local Pakeha. When his raupo hut burned down in 1829, Taiwhanga replaced it with a European-style cottage. Having become an able letter writer in the mid 1820s, he was a monitor at the Paihia mission school from 1830 to 1834.
Taiwhanga's long association with the CMS missionaries led to his baptism at Paihia on 7 February 1830. Six months previously four of his children had been baptised, and Mata followed her husband on 19 September 1830. Taiwhanga was a man of rank and influence and his acceptance of Christianity was the first conversion of note. Baptised Rawiri (David), he became an apostle of his new faith, preaching frequently and vigorously at settlements in the Bay of Islands, Hokianga and Whangaroa. Among the drunken seamen at Kororareka (Russell) he gave testimony of Christianity, and on at least one occasion attended a dying sailor. He accompanied Thomas Chapman and Henry Williams to Tauranga and Rotorua when they took the Christian message there in 1831, and had a central role in explaining their mission to local tribes, including his wife's relations.
From around 1834 Taiwhanga established a thriving farm on the east side of Kaikohe, where he remained until his death. For a time he ran a school but his main efforts went into building up the farm. Having purchased the necessary tools, he made his own plough, and by the end of 1835 was making butter for sale. A year later he had 20 head of cattle and was regularly selling butter to a merchant at the Bay of Islands. By the early 1840s the farm had a small flock of sheep and Taiwhanga had built a new weatherboard house with a chimney. The farm butter, over five years, sold at prices ranging from 1s. to 2s. 6d. a pound. These transactions are the earliest regular sales of dairy produce known in New Zealand and make Taiwhanga the country's first commercial dairy farmer. A contemporary European account describes him as 'an industrious man of business, well knowing how to strike a bargain'.
For Taiwhanga, as for many of his contemporaries, Christianity and the adoption of European materials and methods went together. Heavily tattooed and of stocky build, Taiwhanga began to wear European clothing in the 1820s and taught his children European ways. While Mata was alive he submitted to the missionary ruling that he could not marry more than one woman. The missionaries spoke of him as 'one of ourselves' and Taiwhanga associated his interests with those of the missionaries. In 1831 he suggested appealing to Britain for protection against supposed French threats and at the Waitangi treaty negotiations in 1840 he spoke in favour of accepting William Hobson as governor. Subsequently he put his name, Rawiri, in writing, on the treaty. An association with Bishop G. A. Selwyn, resident briefly at Waimate North in the mid 1840s, encouraged Taiwhanga to appeal to him for help after the northern war. Taiwhanga, aware that the war had caused a decline of Christian commitment, hoped that the loss might not be irreparable, and sought Selwyn's support for his local school.
Taiwhanga's work through the following decades is not recorded; nor is it clear whether he lived to see his son Tamati Hirini (Thomas Sydney) become active in the Treaty of Waitangi movement in the 1870s. He is last mentioned by Sven Berggren, a visiting Swedish scientist who met him at Kaikohe in 1874, when he was reputed to be 100 years old.