New Zealand and Tonga
The scientifics arrived in New Zealand on 24 February. They had difficulty securing passage there, and as a result, did not spend as much time exploring the interior of Australia as they hoped. Their time in New Zealand was similarly limited. The scientists had arrived just in time to witness the signing of a "treaty" between Maori chiefs and the British Government. Not a treaty at all, Wilkes believed, but a wholesale cession of the lands of the north island to the protection of Great Britain, which would quickly force a lifestyle on the Maori that they did not desire. Wilkes was particularly sorry that the gentleman holding the title of American Consul, who was in fact an Englishman, had used his influence to induce the chiefs to accept the treaty. Wilkes cited it as evidence that officials of the United States government in foreign places needed to be United States citizens.
Travels inland included a visit home by an expedition crewman who was Maori, John Sac, and some of the scientifics who ventured a short distance along the coast to a place called Wangara. The explorers also prepared a shipment of specimens and letters home to travel with the ship Lydia, which was bound for Salem, Massachusetts. Peacock being under repair at Sydney, the scientifics assigned to it, Alfred Agate included, temporarily boarded Vincennes for the voyage to Tonga. The ships departed New Zealand on 6 April.
They arrived at the islands of Eooa (Eua) and Tongataboo (Tongatapu) on the 24th. The area was poorly charted and had many shoals, so Wilkes immediately sent Porpoise and Flying Fish to the eastern islands for survey duty. Vincennes entered Tonga harbor just as a council of Christianized chiefs was meeting to plan a retaliatory attack against non-Christian cannibal chiefs. War seemed imminent, so Wilkes offered his assistance as mediator. His efforts failed. As details appeared, it became clear that, like most wars, the conflict was over power rather than religion or morality. Neither side could be dissuaded from its ambition.
While at Tonga, the expeditionaries encountered people visiting from other islands and took note of the differences in physical characteristics. These included men from the islands of Rotuma and Erromango.