Tension had been high around Wellington since 1842 particularly concerning the fertile bottom land of the Hutt Valley. The occupants, Nga Rangatahi were determined to retain possession. They assembled a force of about 200 warriors led by Te Rangihaeata, one of the participants in the Wairau Massacre. The British began moving men into the area and by February had assembled nearly a thousand men together with some Maori allies from the Te Atiawa hapu.
The conflict started in February 1846 with both sides plundering and destroying each other's property. The British probably struck first when on February 27th they burnt the Maori settlement at Maraenuku. Te Rangihaeata then began to systematically destroy the settlers farms and property in the Hutt Valley. However at this stage he appears to have deliberately avoided attacking persons and caused no casualties however that soon changed. On 3rd March he attacked a company of militia but was driven off. Governor Grey then declared Matial Law and strengthened the garrisons.
On April 2nd, 1846, two settlers were murdered, possibly by men answering to Te Ragihaeata. On 16th May there was a major attack on a defended position; Boulcott's Farm, one of the most forward homesteads in the Hutt Valley. The siege lasted several hours before reinforcements arrived and the Maori withdrew leaving behind sixteen British casualties. A month later an armed patrol in the same area was ambushed and four men wounded.
Meanwhile the British had effected a landing on the coast north of Wellington. They could have attacked the Maori from the rear and also cut off the flow of reinforcemnts from the Wanganui area. Instead the British commander, Major Last, wasted time building a strong fortress near Porirua. This gave Te Rangihaeata enough time to build his own fortress or Pa at Pauatahanui from where he could block any further British advances from that direction.
They successfully defended this against a British attack on August 5-7th and then withdrew.
This was effectively the end of the Hutt Valley Campaign. Te Mamaku returned to the Wanganui region. Te Rangihaeata built himself a strong Pa near the Manawatu River from which he was able to block European penetration onto that area until he died in 1856.
The Maori were not beaten. Indeed until now they appear to have had the better of all the skirmishes. They simply withdrew and chose to no longer resist European settlement into some area. There were probably several reasons for this. With their main stronghold in the Wanganui area, some distance north, they were operating with extended supply lines and were short of food and ammunition. This problem was considerably aggravated when a shrewd move by Grey recruted the Te Atiawa to his side
However, the principal factor was probably the British decision to arrest the paramount chief of the area, Te Rauparaha. He had been the other main protagonist in the Wairau Massacre and was Te Rangihaeata's uncle. Hitherto he had been inactive in the conflict and there was no evidence to justify his arrest. The move was taken to forestall any trouble he might cause. Justified or not, the effect on Maori morale was great and it seems to have been a strong factor in their decision to end the campaign.