The Pioneer was an iron-clad, sternwheel paddle steamer, built at Pyrmont in Sydney for military operations in the Waikato. Commissioned by February or March 1863, it is believed to have been the first purpose-built warship ordered by the colonial authorities in New Zealand. The vessel was constructed at a cost of £9,500 by the Australasian Steam Navigation Company under the supervision of Tom McArthur, and was modelled on a design by Captain Cowper Coles (1819-1870). Coles was a British naval officer and a member of the Royal Institution of Naval Architects, who is considered to have invented the rotating gun cupola in 1859. His ideas were successfully adapted during the American Civil War in 1862, after which he went on to design large gunboats, including the Captain, in which he drowned when it capsized in 1870. The rotating cupola, or turret, represented a major innovation in naval military technology, allowing gunships to fire at will without having to manoeuvre into a broadside position. The first European warship equipped with Coles' turrets is said to have been the Rolf Krake, launched for the Danish navy in May 1863.

The manufacture of the Pioneer and the modification of another vessel into an iron-clad gunship - the Avon - caused concern among Maori in the Waikato, leading to calls from the Kingitanga movement in February 1863 that the steamers should not be allowed to enter their waters. Construction of the vessel nevertheless proceeded and took just seventeen weeks, being completed in July 1863. Built for river conditions, the steamer was towed across the Tasman to Onehunga by the Eclipse, arriving in the Manukau Harbour on 3 October 1863. The colonial authorities subsequently handed the vessel over to a British naval crew, who used it in action on the Waikato River before the end of the month.

Originally named Paparata, and later Waikato, the Pioneer measured 43 metres long and was 7 metres wide. It was powered by two 30-hp engines through paddles that were 4 metres in diameter and a little over 2 metres wide. Created with a flat-bottomed hull that drew less than one metre, the vessel was designed to pull barges capable of carrying 300-400 men. It was fully armour-plated to withstand rifle shot and was armed with two rotating Armstrong twelve-pound guns - or possibly larger artillery - located in its cupolas fore and aft. The Pioneer is likely to have been one of the earliest vessels in the Southern Hemisphere to have employed this technology.

The Pioneer played an instrumental part in the military campaign to defeat the Kingitanga forces during the Waikato - or third New Zealand - War, which had begun in July 1863. It was used to transport troops and supplies to the battlefields, to reconnoitre enemy positions, and to shell defended pas, taking part in the battles at Meremere and Rangiriri. Its deployment for artillery fire is said to have persuaded King Tawhiao (?-1894) to abandon his gun-fighting pa and headquarters at Pikirero in Ngaruawahia, which was vulnerable to shelling from both the Waikato and Waipa Rivers. The Pioneer subsequently transported 500 British troops to Ngaruawahia on 8 December 1863, where they converted the empty pa into a redoubt and supply base for the remaining campaign. One of the gun turrets was removed to lighten the vessel's load later in the same month, possibly at Ngaruawahia, while the second turret was taken off shortly afterwards at Mercer. The Pioneer itself was used to transport supplies and settlers into the Waikato region immediately after the war, and eventually sank on the Manukau bar in December 1866.

Following its removal from the Pioneer, the turret at Mercer became a lock-up and later a First World War Memorial, while the other was placed at The Point - then known as the Regatta Grounds - in Ngaruawahia in 1927. This turret was presented to the town by the Minister of Internal Affairs, R. F. Bollard, on behalf of the Government and was officially opened on Regatta Day. Initiated in the early 1890s, the Ngaruawahia Regatta was an important cultural and social event in the township, celebrating the settlement's links with its two rivers. The presentation occurred shortly after the Kingitanga movement had symbolically returned to its original home and headquarters, constructing a parliament building on or next to Pikirero pa in 1912-1919, and founding Turangawaewae Marae on the opposite side of the Waikato River in the early 1920s. The regatta grounds themselves had been created after 1907, when a large flood devastated the houses and commercial wharf that had previously occupied The Point. A previous memorial to war had been erected at The Point in 1922, when a cenotaph to the First World War was unveiled.

The turret was initially positioned towards the northern end of the regatta grounds, near a 1912 band rotunda. Prior to 1976, it was moved to another site nearby to cover up an earlier water supply. It has since been relocated to its current position on the western side of the grounds, which is closer to the site of Pikirero pa. Serving as a reminder of the Waikato War and its consequences - including the confiscation of nearly 500,000 hectares of Maori land by the colonial authorities - the structure has been recently provided with interpretative panels outlining its history, and forms part of the Kingitanga Heritage Trail.