The New Zealand Wars took place from 1845 to 1872 between the New Zealand Colonial government and allied Mori on one side and Mori and Mori-allied settlers on the other. They were previously commonly referred to as the Land Wars or the Mori Wars, while Mori language names for the conflicts included Ng pakanga o Aotearoa ("the great New Zealand wars") and Te riri Pkeh ("the white man's anger"). Historian James Belich popularised the name "New Zealand Wars" in the 1980s, although the term was first used by historian James Cowan in the 1920s.Though the wars were initially localised conflicts triggered by tensions over disputed land purchases, they escalated dramatically from 1860 as the government became convinced it was facing united Mori resistance to further land sales and a refusal to acknowledge Crown sovereignty. The colonial government summoned thousands of British troops to mount major campaigns to overpower the Kngitanga (Mori King) movement and also acquire farming and residential land for British settlers. Later campaigns were aimed at quashing the so-called Hauhau movement, an extremist part of the Pai Mrire religion, which was strongly opposed to the alienation of Mori land and eager to strengthen Mori identity.At the peak of hostilities in the 1860s, 18,000 British Army troops, supported by artillery, cavalry and local militia, battled about 4,000 Mori warriors in what became a gross imbalance of manpower and weaponry. Although outnumbered, the Mori were able to withstand their enemy with techniques that included anti-artillery bunkers and the use of carefully placed p, or fortified villages, that allowed them to block their enemy's advance and often inflict heavy losses, yet quickly abandon their positions without significant loss. Guerrilla-style tactics were used by both sides in later campaigns, often fought in dense bush. Over the course of the Taranaki and Waikato campaigns, the lives of about 1,800 Mori and 800 Europeans were lost, and total Mori losses over the course of all the wars may have exceeded 2,100.

Violence over land ownership broke out first in the Wairau Valley in the South Island in June 1843, but rising tensions in Taranaki eventually led to the involvement of British military forces at Waitara in March 1860. The war between the government and Kngitanga Mori spread to other areas of the North Island, with the biggest single campaign being the invasion of the Waikato in 18631864, before hostilities concluded with the pursuits of Riwha Ttokowaru in Taranaki (18681869) and Rangatira (chief) Te Kooti Arikirangi Te Turuki on the east coast (18681872).

Although Mori were initially fought by British Army forces, the New Zealand government developed its own military force, including local militia, rifle volunteer groups, the specialist Forest Rangers and kpapa (pro-government Mori). The government also responded with legislation to imprison Mori opponents and confiscate expansive areas of the North Island for sale to settlers, with the funds used to cover war expenses; punitive measures that on the east and west coasts provoked an intensification of Mori resistance and aggression.

The Wairau Affray (called the Wairau Massacre in many older texts) on 17 June 1843 was the first serious clash of arms between British settlers and Māori in New Zealand after the signing of the Treaty of Waitangi and the only one to take place in the South Island. The incident was sparked when a magistrate and a representative of the New Zealand Company, who held a possibly fraudulent deed to land in the Wairau Valley in Marlborough in the north of the South Island, led a group of European settlers to attempt to clear Māori off the land and arrest Ngāti Toa chiefs Te Rauparaha and Te Rangihaeata. Fighting broke out and 22 British settlers were killed, nine after their surrender. Four Māori were killed, including Te Rongo, who was Te Rangihaeata's wife and Te Rauparaha's daughter.

The incident heightened fears among settlers of an armed Māori insurrection. It created the first major challenge for Governor Robert FitzRoy, who took up his posting in New Zealand six months later. FitzRoy investigated the incident and exonerated Te Rauparaha and Te Rangihaeata, for which he was strongly criticised by settlers and the New Zealand Company. In 1944 a land claims commission investigation determined that the Wairau Valley had not been legally sold. The government was to pay compensation to the Rangitāne iwi, determined to be the original owners (until the early 1830s, when Te Rauparaha had driven them from the area).