The British invasion of Waikato began on 12 July 1863. Because of their comparative lack of men and supplies, the Kingites’ strategy was to construct defensive lines to obstruct the British advance and frustrate the troops. A similar strategy had been effective in Taranaki in 1860–61. The first line of defence was at Meremere. After this was bypassed, Rangiriri and Pāterangi provided a second and then a third barrier to the invaders.
Following the initial invasion on 12 July the 65th Regiment established the Alexandra Redoubt on a hill above the Waikato River. From here the British aimed to secure control of the lower reaches of the river and protect the supply lines of the invasion force. The fight to control the heights above the Waikato River began on 17 July at Koheroa. Te Huirama (Ngāti Mahuta) led up to 150 men in this battle but was forced to retreat when Cameron attacked his positions. Some 14 or 15 Māori were killed, with the British suffering only one fatality. The invaders were now able to build a redoubt facing their principal target, the Māori defences at nearby Meremere.
Between July and October a number of skirmishes occurred in South Auckland and along the Great South Road. Redoubts protecting settlements and the Great South Road itself were gradually manned by regiments of Waikato Militia recruited in Australia. This enabled Cameron to free up his regular forces for operations further south. Historian James Belich argues that this skirmishing succeeded in delaying Cameron. On the other hand, Pugsley believes that these diversions had little impact on Cameron’s original plans: the initial move in July had always been intended to establish a foothold and prepare for a summer campaign. He was ready to commence this at the end of October.
At its peak the Māori force at Meremere numbered perhaps a thousand men under the overall command of the Ngāti Haua leader Wiremu Tāmihana. Every tribe which acknowledged the authority of King Tāwhiao had warriors at Meremere.
The Māori force had three ships’ guns which had been given to Ngāti Tahinga by a trader many years earlier. These guns were carried overland from Raglan, then brought downstream by canoe. A former East India Company gunner living in the Waikato was forced to train Kingite warriors to fire these weapons. But Māori had no ammunition for these guns. They were forced to fire improvised shells made of iron chain, nails and pound weights that had little effect on armoured vessels.
Cameron assembled an armoured river fleet to carry men and supplies for the assault on Meremere. The paddle-steamer Avon had been readied for war at Onehunga in 1862. It was armed with a 12-pounder ship’s gun and a Congreve rocket tube, and iron-plated for protection from enemy fire. Four armoured barges were also prepared as troop carriers. This fleet was boosted by the arrival in October 1863 of the Pioneer. Capable of carrying 300 men, this ‘rifle gunboat’ was the first naval vessel built for the New Zealand government.
On 31 October 1863, 600 men of the 40th and 65th regiments and two 12-pounder Armstrong guns were loaded onto the Pioneer, the Avon and the four barges, which were towed by two steamers. The convoy was fired at as it steamed past Meremere, but landed 10 km upriver. Cameron’s plan was to cut off Meremere from its support at Pukekawa on the other side of the river and attack the Māori position from both north and south. Meremere’s defenders were outflanked and had little choice but to withdraw to the east. The next day the British occupied the abandoned position. The first major obstacle on the river had been removed, but Cameron had been unable to draw the Māori force into a costly battle. He would have to move further south to Rangiriri to achieve a decisive victory.