The East Cape War, sometimes also called the East Coast War, was a series of conflicts fought in the North Island of New Zealand from April 1865 to October 1866 between colonial and Māori military forces. At least five separate campaigns were fought in the area during a period of relative peace in the long-running 19th century New Zealand Wars.

The east coast hostilities came at the close of the Waikato wars and before the outbreak of Te Kooti's War, both fought nearby, but sprang from causes more closely related to the Second Taranaki War—namely, Māori resentment of punitive government land confiscation coupled with the rise of the so-called Hauhau movement, an extremist part of the Pai Marire religion (also called the Hauhau), which was strongly opposed to the alienation of Māori land and eager to strengthen Māori identity.

Pai Mārire arrived on the east coast from Taranaki about 1865. The subsequent ritual killing of missionary Carl Volkner by Pai Mārire followers at Ōpōtiki on 2 March 1865 sparked settler fears of an outbreak of violence and later that year the New Zealand government launched a lengthy expedition to hunt for Volkner's killers and neutralise the movement's influence. Rising tensions between Pai Mārire followers and conservative Māori led to a number of wars between and within Māori iwi, with kūpapa or "loyal" Māori armed by the government in a bid to exterminate the movement.

Major conflicts within the campaign included the cavalry and artillery attack on Te Tarata pā near Ōpōtiki in October 1865 in which about 35 Māori were killed and the seven-day siege of Waerenga-a-Hika in November 1865. The government, claiming that one of Volkner's killers was being given sanctuary by Māori in the remote Urewera region, confiscated northern parts of the Urewera land in January 1866 in a bid to break down Māori resistance and confiscated additional land in Hawke's Bay a year later after a rout of a Māori party it deemed to pose a threat to the settlement of Napier. In 2013 the Crown paid $23 million in financial redress and expressed "profound regret" over the "unjust attacks" in Hawke's Bay in 1866 and apologised for subsequent land confiscations.

Background In 1863 the government enacted laws to confiscate the land of Māori deemed to have been "in rebellion" against the government in the land wars. The laws were aimed at punishing Māori for their aggression and also establishing law, order and peace by using areas within the confiscated land to establish settlements for colonisation. From early 1865 the government began confiscating wide areas of Taranaki and Waikato, depriving Māori of their food sources and livelihood. In many parts of the North Island, the resultant resentment and anger found expression in the more radical, nationalistic elements of Pai Mārire, which sought to drive European settlers from the land.

Pai Mārire had begun in Taranaki as a peaceful religion, a combination of Christianity and traditional Māori beliefs, but by 1865 had developed a reputation as a violent and vehemently anti-Pākehā (European) movement. The arrival and rapid spread of Pai Mārire in the East Cape destabilised the region, dividing Māori communities and also causing great alarm among New Zealand settlers despite the fact the area was almost devoid of European settlement. The government responded with several ad hoc measures, including supplying arms to "loyal" factions, organising a force of Arawa tribesmen under European leaders, and a series of small expeditions of volunteer settlers from Hawke's Bay.

Killing of Carl Volkner In early 1865 Pai Mārire leader Te Ua Haumēne sent two prophets, Kereopa Te Rau and Patara Raukatauri, to convert East Coast tribes. Kereopa, an ageing veteran of the Waikato wars, carried with him the head of Captain P. W. J. Lloyd, who had been killed in the Ahuahu attack of April 1864 in Taranaki. Kereopa had lost his family in the bloody British raid on Rangiaowhia the previous year and blamed much of the massacre of women and children on missionary complicity, so he and his followers sought utu, or revenge, against missionaries. In Whakatane he demanded that Ngāti Awa iwi hand over the local Roman Catholic priest; without waiting for a result the pair continued on to Ōpōtiki, where they succeeded in winning the allegiance of local Māori from the Whakatohea iwi to the Pai Mārire creeds. German-born Lutheran missionary Carl Sylvius Volkner, who had lived in Ōpōtiki for four years, was absent in Auckland and Patara, believing the cleric was acting as a government spy, wrote him a letter stating that missionaries would henceforth not be permitted to live among Māori and ordered him not to return. Ignoring warnings that his life was in danger, Volkner sailed back to Ōpōtiki, arriving on 1 March. The schooner was looted and Volkner and another missionary, Thomas Grace, were taken captive. The following day Volkner was hanged, then beheaded. In a church service that followed, Kereopa swallowed Volkner's eyes—momentarily choking on one of them—and passed around a chalice containing the missionary's blood for it to be consumed by his congregation. Grace remained captive for two weeks before escaping.

A poorly-armed Māori party led by chiefs including Ropata Wahawaha mounted an unsuccessful raid on Pai Mārire adherents at Mangaone, near Pukemaire, on 10 June 1865. After several more small engagements in the Waiapu Valley a delegation of east coast chiefs led by Mōkena Kōhere appealed to Donald McLean, the new Provincial Superintendent of Hawke's Bay, for arms and reinforcements to subdue the uprising. McLean immediately supplied Mokena with weapons and ammunition, then dispatched about 100 Colonial Defence Force troops under Major James Fraser. landed the troops at Hicks Bay and at the mouth of the Waiapu River on 5 July 1865 in a bid to capture Kereopa and Patara, shelling their Hauhau enemy the next day. When a trading cutter following the troops anchored off Whakatane on 22 July to allow surveyor and government interpreter James Fulloon to go ashore to investigate the local mood, it was boarded by Pai Mārire converts at the orders of Taranaki prophet Horomona. Fulloon and two of its crew were shot and killed and the vessel's mast was taken ashore and erected as a niu or sacred pole for Pai Mārire rites.

East Coast expedition In Auckland, fears grew that the spread of Pai Mārire could unite tribes against settlers in a tide of religious fanaticism. The problem posed a major challenge for the cash-starved government which, already under pressure from London to release British troops for overseas deployment, had deployed the bulk of available forces in Taranaki and Wanganui, where much of their foe was also aligned with Pai Mārire. Without informing the British commander in New Zealand, General Duncan Cameron, Governor George Grey delegated large powers to McLean to use friendly Māori and local volunteers to put down disturbances and punish Volkner's killers.

Fraser's force continued to strike at Pai Mārire villages through July and August with further significant help from Ropata: 25 enemy were killed and about 30 prisoners taken in a raid on Pa-kairomiromi in the Waiapu basin on 2 August, while eight of Fraser's men were wounded. The captured stockade was then burned. When Pai Mārire forces launched an unsuccessful raid on a loyalist Māori pā at Tokomaru Bay under the control of Ngāti Porou chief Henare Potae, Henare requested help from Ropata, who led a reprisal raid on two nearby Pai Mārire positions, Pukepapa and Tautini pā. Though outnumbered 500 to 200, Ropata captured the positions, then used a revolver to execute prisoners from his own tribe who had converted to the religion. On 18 August at a pā between Tokomaru and Tolaga Bay a heavily outnumbered force of 36 men under Henare Potae was reinforced by another 90 under Ropata in a sharp and bloody engagement. Twelve of the Pai Mārire were killed, prompting survivors to abandon the East Cape region and flee south to the Waerengaahika pā in the Tūranganui (Poverty Bay) region.

On 2 September 1865 the government declared martial law on the east coast and announced a new expedition against Volkner's killers, threatening confiscation of land in the area if they were not handed over. The expedition was an entirely colonial force, consisting of Taranaki Military Settlers, Wanganui and Patea Rangers, Wanganui Yeomanry Cavalry, and the Wanganui Native Contingent under Major Thomas McDonnell, and all under the overall command of Major Willoughby Brassey. The 500 troops sailed from Wellington and Wanganui and rendezvoused off Hicks Bay on 7 September, joining additional troops who had sailed from Auckland, including former Forest Ranger commander Major Gustavus von Tempsky.

A small initial landing force came under fire as it attempted to land in gale-force winds and was reinforced with the remainder of the troops the next morning, driving the Māori defenders several kilometres inland. Eight Whakatohea Māori were killed in the two-day clash.

The expeditionary force remained in Ōpōtiki for several weeks, converting Volkner's church into a redoubt and engaging in occasional clashes with Māori, who established the entrenched and palisaded Te Puia pā about 8 km inland. On 4 October McDonnell led a force to Te Tarata, a new pā about 6 km from Ōpōtiki. When the force came under heavy fire, McDonnell sent for cavalry and artillery reinforcement, who surrounded the pā on three sides and began shelling it. As Māori reinforcements began arriving from nearby Te Puia, the cavalry charged through them with swords, killing and wounding about 20. McDonnell's forces maintained heavy fire on Te Tarata past nightfall. About 8 pm a member of the Whakatohea garrison called out, asking for terms of surrender. McDonnell told them Volkner's killers would be tried and the rest would be prisoners of war. The garrison requested an hour's truce while they considered the request, but under cover of darkness launched a breakout, rushing the Rangers while firing their shotguns, then engaging in hand-to-hand battle with revolvers and tomahawks. About 35 Māori were killed and 35 wounded, and three of the colonial forces killed. The East Coast Expedition, now under the control of Major Charles Stapp, moved its base to the captured Te Puia and the Whakatohea fell back to new strongholds in the Waioeka Gorge. Soon after about 200 of the Ngati-Rua hapu of Whakatohea surrendered to Stapp; Ngati-Ira, under Hira Te Popo, remained hostile.

In mid-October McDonnell commanded a three-day expedition in which a force of 150 marched into the Waimana Valley in a bid to capture Kereopa and his followers. Early on 20 October the force reached Koingo, a small village on the Waimana River and set up an ambush of a track; Kereopa was targeted but escaped, although five others accompanying him were shot. Troops then raided the village, killing three Urewera and Ngai Tama Māori and capturing several others. The East Coast Expedition's activities continued till November, prompting the surrender of more Māori including a chief, Mokomoko, whose rope had been used in Volkner's hanging; he was later tried and hanged in Auckland. Another 18 were also tried.

In November 1865 the Native Contingent returned to Major-General Trevor Chute's west coast campaign, while the Rangers and 1st Waikato Militia remained in occupation of Ōpōtiki; the Patea Rangers were recalled to the west coast in May 1866.

Pukemaire In mid-August 1865 an East Coast Field Force, including members of the Waikato Militia, was formed under the command of Major Willoughby Brassey. Supplemented by volunteers recruited in Napier by Captain Charles Westrup, the force sailed on HMS Brisk to Gisborne, where they built a redoubt, before continuing on 30 September to Waiapu, near East Cape, to reinforce Fraser's force.