After the signing of the Treaty of Waitangi on 6 February 1840, no specific arrangements were made for the defence of the colonists. Early hopes of peaceful relations between Maori and Pakeha soon faded and, among other factors, the absence of a strong British military force acted as a continued source of provocation to some Maori chiefs. The Maoris were an intelligent and warlike race, organised as tribes, and experienced in the use of firearms, and they heavily outnumbered the 11,000 or so Europeans grouped in seven coastal settlements. Friction arose principally over land claims, and the first clash, the “Wairau Affray” occurred in the South Island on 17 June 1843, when Te Rauparaha and Te Rangihaeata opposed a party of Nelson (New Zealand Company) surveyors and settlers and killed 22 of them. The encounter had unfortunate repercussions. Trouble soon spread to North Auckland where there were local land disputes, aggravated by a decline in trade consequent upon Hobson's decision to transfer the capital to Auckland. Maori discontent was widespread and Hone Heke felt emboldened to show his defiance of British authority. On 8 July 1844 Hone Heke and Kawiti led a well armed force which sacked Kororareka after a sharp encounter with soldiers and sailors from HMS Hazard and volunteer civilians.

The New Zealand Army (which owes its genesis to this outbreak) has seen many changes of form in its short history. At first it consisted of militia battalions formed in Auckland, Wellington, and Nelson, where settlers feared Maori attacks. Then, after a period of comparative peace, there was a resurgence of militia activity; the growth of a volunteer force; the establishment of special groups in the later Maori Wars; their disbanding when peace was restored; the formation of an armed constabulary from which stemmed the Permanent or Regular Force; and, finally, the establishment of the Territorial Force. The Army's Regular component has always been small, but underlying all policies there is the concept of a “citizen army”, a force that, with good leadership, training, and equipment, has been the equal of any professional army. In the beginning reliance was placed on experienced officers who had served in British regiments in many parts of the world, and ever since there has been considerable dependence upon British advice.

The principal concern of the early colonists was to create a new life for themselves, and only as a last resort were they prepared to take up arms against troublesome Maoris. It was considered to be the British Government's responsibility to provide troops for internal defence and security. At first the Imperial authorities accepted this by assuming full responsibility both for Maori affairs and for defence. After the attainment of self-government, and on the outbreak of war in 1860, the colony was expected to subsidise British troops in New Zealand and to supplement these by locally raised forces. British regiments bore the brunt of the fighting in the Maori Wars at least until the mid-1860s.