The Battle of Ōhaeawai, part of the Flagstaff War, was fought in July 1845 at Ōhaeawai in Northland, New Zealand. The battle was between British forces and their allies from the local Ngāpuhi tribe of Māori on one side, and other Ngāpuhi, led by Te Ruki Kawiti, a prominent rangatira (chief), on the other side. The battle was notable for establishing that an appropriately built fortified pā could withstand bombardment from cannon fire, with a frontal assault by soldiers suffering heavy casualties.

The Flagstaff War, also known as Heke's War, Hōne Heke's Rebellion and the Northern War, was fought between 11 March 1845 and 11 January 1846 in and around the Bay of Islands, New Zealand. The conflict is best remembered for the actions of Hōne Heke who challenged the authority of the British by cutting down the flagstaff on Flagstaff Hill at Kororāreka. The flagstaff had been a gift from Hōne Heke to James Busby, the first British Resident. The Northern War involved many major actions, including the Battle of Kororāreka on 11 March 1845, the Battle of Puketutu on 8 May 1845, the Battle of Ōhaeawai on 23 June 1845 and the siege of Ruapekapeka Pā from 27 December 1845 to 11 January 1846.