In 1863, during the Waikato-Hauhau Maori War in New Zealand, the "Harrier" participated in an expedition up the Waikato River in support of British Army operations. Mitchell, who had been made captain of the foretop, was part of a naval brigade that was raised for service in the Invasion of the Waikato and which fought in the Battle of Rangiriri. By the end of the year, the fighting in the Waikato region had ceased but hostilities had shifted to Tauranga, and Mitchell's brigade moved there to participate in the Tauranga Campaign.