"This large redoubt, on the right bank of the Lower Waikato, was built in July, 1863, by a detachment of the 65th Regiment. The position, on a bold bluff about 300 feet above the river, was commanding and of great strategic importance. The redoubt is the best preserved of all the military posts built in 1863–64. The present entrance is from the roadway in the rear into the north-west flanking angle, where a monument erected by the Government bears the names of British soldiers who fell in the district."
More on the redoubt here.