[5] He became known as hoa pili which means "close personal friend" in the Hawaiian language because of his trusted relationship with Kamehameha.

When his nephew Keaoua Kekuaokalani organized an uprising, Hoapili was sent with chief orator Naihe to negotiate a peaceful settlement.

Kekuaokalani refused, so Hoapii and military leader Kalanimoku led Kingdom troops to the battle of Kuamoʻo where the rebels were routed.

Although Kamehameha II was officially King, real power was held by Hoapili's half-cousin Queen Kaʻahumanu, who welcomed them.

In February 1823, Keōpūolani renounced the practice of multiple spouses for royalty, and made Hoapili her only husband.

[10] In May 1823 he and Keōpūolani moved to Lahaina on the island of Maui, and asked for books and a chaplain so they could continue their studies.

[citation needed] They adopted and helped raise Prince Lot Kapuāiwa (Kalākua's grandson, who would later come to the throne as King Kamehameha V) in the Hawaiian tradition known as hānai.

[14]: 292 In August 1824, Hoapili led troops from Maui to suppress an uprising by "George Prince" Kaumualiʻi on Kauaʻi.

Hoapili ordered cannon to defend the town after an irate captain of the English whaler John Palmer had opened fire on the mission station.

[14]: 246 As more companies of missionaries arrived, Hoapili awarded them additional grants of land, sometimes to the consternation of the people who lived there.

Dwight Baldwin arrived in 1836, and would help Hoapili deal with the health problems of alcoholism and epidemic diseases carried on the whaling ships.

[12]: 259 [18] Historian Sheldon Dibble called Hoapili "a meek and quiet disciple of Jesus and a firm supporter of the Christian Religion".