Pomare II, known as Whiria as a young man, was born in the latter part of the eighteenth century. He lived in the southern Bay of Islands, in the territory of Ngati Manu, of Nga Puhi. His connection to this hapu was through his mother, Haki, the elder sister of Whetoi, also known as Pomare or Pomarenui. Whiria's father was probably of lesser but still respectable rank; he was Tautoro (Te Tautoro), a descendant of Rangi-heke-tini and Hineira. Whiria was related to Tara of Kororareka (Russell) and to his heir, Te Whareumu, also of Ngati Manu.
By 1815 Whiria was chief over a village in the Waikare district. He was reported by the newly arrived missionaries to be graceful, well proportioned, strong, and attractive to women. He had several wives and children, including a boy aged about nine. He was already heavily involved in trading with European shipping, and eager for some European settlement in his area.
On the death of his uncle, Pomare, while on a raid in Waikato in 1826, Whiria assumed the names Whetoi and Pomare to remind his people of their duty to avenge their former leader. In 1828 both Te Whareumu and the only surviving son of Pomare I, Tiki, were killed in a dispute with Te Mahurehure hapu of Waima. Although Kiwikiwi, the brother of Te Whareumu, was recognised as Te Whareumu's heir, his influence was never very great; the emergence of the younger Pomare as a principal chief began at this time.
In 1830 Pomare's position was consolidated. In the same year two Nga Puhi women who were living with Captain W. D. Brind in Ngati Manu territory at Kororareka were bathing one day. Women of Ngati Manu ducked them in horseplay which soon deteriorated into serious fighting. Te Urumihia, wife of Kiwikiwi, came to the rescue of the Ngati Manu women, and cursed Brind's women, Pehi, the daughter of Hongi Hika, and Moewaka, the daughter of Rewa. The curse was reported to Hongi Hika's kinsman Ururoa, also known as Rewharewha, who brought a war party from Whangaroa to raid the plantations of Ngati Manu. An armed clash resulted, which became known as the Girls' War; upwards of 100 from both sides were killed, but on the whole the forces of Pomare and Kiwikiwi were the victors.
Among the dead was the important chief Hengi of Ngati Rehia, an ally of Ururoa. After his body had been removed Titore set out to avenge his death. He threatened to attack Kororareka pa unless Pomare and Kiwikiwi had left by the next morning. Ngati Manu abandoned their position and withdrew, first to Paihia, and then to Pomare's pa at Otuihu. There they built a new pa, so constructed as to allow for the use of cannon. Although Kiwikiwi retained his position as chief, his status as a refugee in Pomare's territory allowed the more forceful Pomare to achieve a position of dominance among Ngati Manu.
Kororareka, the most important anchorage and trading centre in the Bay of Islands, was the great prize for which the northern alliance of Nga Puhi hapu had been angling for some years; the quarrel of the women had merely provided the excuse. The determination of its conquerors to hold on to it, and of Pomare to regain it, was to dominate local Maori politics for some years. Rumours that northern Nga Puhi hapu were about to attack Pomare at Otuihu were rife in 1832, and again in 1834.
Pomare put most of his energy into making Otuihu both impregnable and a rival to Kororareka as a centre of attraction for Europeans. He became a major dealer in spirits, several grog shops were established in the pa, and he may have possessed his own still. He traded in pork, potatoes and timber, derived profit from the prostitution of the slave women of the pa, and encouraged gambling.
Quarrels over Kororareka were not Pomare's only battles. He led war parties south in 1827 and 1832; in the first of these campaigns he succeeded in killing Te Hou, and sold his preserved head to French explorer Dumont d'Urville. He was involved in hostilities against Ururoa again in 1832–33, and with Waikato of Rangihoua in 1836.
Pomare did not tolerate offence towards himself or his property by Europeans; he seized their possessions in recompense, including Captain James Reddy Clendon's whaleboat in 1832, and Thomas King's boat in 1833. The latter event led to a dispute with the British Resident, James Busby, which was only successfully arbitrated by CMS missionary Henry Williams when the warship Alligator anchored just off Pomare's pa in 1834.
A three month war with Titore in 1837 was an inconclusive affair. At one stage Titore sent about 40 canoes with 800 men in an attempt to take Otuihu. At times there were nearly 3,000 warriors under arms. Pomare was aided by 131 Europeans living in his pa. A peace agreement was negotiated by Tareha, and the subsequent death of Titore ensured a final cessation of the quarrel. The war had important effects as it was witnessed by Captain William Hobson of the Rattlesnake. The report submitted by Hobson, together with Busby's dispatches and a missionary inspired petition, contributed to eventual British intervention in New Zealand.
Pomare signed the Treaty of Waitangi on 17 February 1840 and in May promised to induce Tirarau and Kawiti to sign it also, a promise which he duly carried out. Nevertheless, aspects of British sovereignty offended him. The tolls he had levied for years on British shipping had to end and he shared the concerns of other Maori leaders over the effects of British administration on their mana. Perhaps because of a recent quarrel with Kawiti, Pomare remained neutral when Hone Heke and Kawiti challenged British sovereignty in 1844–46. But some of Pomare's people participated in the spoils when Kororareka was sacked, and the government claimed to have intercepted treasonous letters from Pomare to Potatau Te Wherowhero. As a precautionary measure Pomare was arrested in his pa on 30 April 1845, his people were scattered and his pa rased, despite his flying a flag of truce. Pomare sent a message to Heke saying he wished no action to be taken on his behalf; he was being well treated.
Pomare was taken to Auckland on the North Star, but was released after the intervention of Tamati Waka Nene. He was presented with a boat as some compensation for his treatment. Pomare subsequently put together a war party to assist in the campaign against Heke, but, perhaps fearing to compromise his neutrality, withdrew before the battle of Ohaeawai on 1 July 1845. As a neutral he played an important part in the peace negotiations.
Pomare spent his last few years in relative peace. He accepted the arbitration of the government in a dispute over land, and in the last year of his life became a Christian. He died in July or August 1850.