Like his father, King Tāwhiao opposed the war in Taranaki. The government, however, remained unconvinced. In July 1860 Governor Gore Browne sought to isolate the Kīngitanga and its supporters when he invited about 200 chiefs to a conference at Kohimarama near Auckland. Those deemed to be rebellious, from areas such as Taranaki and Waikato, were not invited. The conference reaffirmed the Treaty of Waitangi and the sovereignty of Queen Victoria, but those present did not endorse the government's line in Taranaki. Nor did they condemn the Kīngitanga.
Gore Browne was not pleased. Public opinion was critical of his performance as governor and no significant progress had been made in Taranaki. A breakthrough came in March 1861 when Wiremu Tamihana visited Taranaki and arranged a truce. Some interpreted his actions as no more than a veiled recruitment drive for the Kīngitanga, despite his success in persuading many warriors to leave the battlefield. Native Secretary Donald McLean concluded negotiations, and the war in Taranaki ended on 18 March 1861. The peace settlement required Taranaki Māori to submit formally to the Queen's authority. In reality few took the oath to the Queen.
In April Gore Browne upped the ante by demanding that the Kīngitanga submit 'without reserve' to the British Queen. His plans for the invasion of Waikato were interrupted when he was re-assigned to Tasmania, but his replacement, Sir George Grey, made similar plans. Colonial policy makers believed Grey's success in dealing with the Northern War and the powerful Ngati Toa leader Te Rauparaha during his first term as governor (1845–53) made him the most qualified man to sort out New Zealand's troubles.
At first Grey used flattery and patronage to try to buy Māori support. Then John Gorst was appointed as resident magistrate for Waikato in an attempt to undermine the Māori King's authority. Through his newspaper, Te Pihoihoi Mokemoke, a rival to Te Hokioi, Gorst ridiculed the King movement.
Grey's plan, should all of this fail, was to use military force to assert European authority. Plans were developed to build a courthouse, in the Waikato, that could double as police barracks. Government roads to Mangatāwhiri and Raglan meant a rapid response was possible in the event of war. A redoubt at Te Ia on the Waikato River was backed-up by plans to place bulletproof steamers on the river. Finally, the Great South Road was built as a supply line for the British army, allowing it to penetrate the heart of Waikato.
War threatened the unity of the King movement. Wiremu Tamihana indicated that his supporters were ready to accept magistrates and courts. Tāwhiao's advisers and immediate followers formed another moderate party committed to peace. A more extreme group among Ngāti Maniapoto was less conciliatory. It was responsible for a number of violent incidents and was ready to fight if challenged.
Grey's position was made abundantly clear at Taupiri in January 1863, when he announced plans to 'dig around the Kīngitanga until it fell'. Tamihana wrote to him pointing out that as different nations in Europe had sovereigns from among their own people, Māori should also be able to choose one of their own. Tamihana's reply was taken as proof that sovereignty was at the root of what was being portrayed as the Waikato rebellion. Rumours of an imminent Māori attack on Auckland increased the tension. A number of violent incidents saw settlers and missionaries flee the Waikato. Grey was able to exploit all of this in securing greater support from London in his request for more manpower.
Fresh fighting erupted in Taranaki in the autumn of 1863 over the government's reoccupation of the Tataraimaka block. Rewi Maniapoto's involvement in an ambush at Oakura gave Grey the excuse he needed. In July he issued all Māori living between Auckland and the Waikato River with an ultimatum: swear allegiance to the Queen and give up arms or be deemed to be in rebellion and face the consequences. Grey was now backed by a force of 18,000 troops, including some Māori forces known as kūpapa or Queenites to distinguish them from the Kīngitanga or Kingite forces.
On 12 July 1863 British troops crossed the Mangatāwhiri stream. The Kīngitanga had declared this to be an aukati (a line that should not be crossed) and considered any breach to be an act of war. The invasion of the Waikato had begun.
Māori described as loyal to the British were often referred to as kūpapa, which meant friendly. Another term used was Queenite, to signify loyalty to Queen Victoria. These Māori were often used as evidence that Māori fighting against the British were rebels or in some way outside mainstream Māori opinion.
Such an interpretation can be misleading. Kūpapa fought against other Māori not necessarily out of loyalty to the Crown but often because the British were fighting traditional rivals and could be exploited to help settle old scores.
Historian Michael King believed kūpapa Māori generally prospered in the aftermath of the New Zealand Wars. Their land escaped confiscation and they received positive government attention and rewards including 'ceremonial swords for their leaders, monuments for their dead, and consultation on some matters of public policy'.