Kamehameha achieved prominence in Hawaii in 1782 at the death of his uncle receiving a prominent religious position. At this time, there was already bad blood between the two cousins when a group of chiefs from the Kona district presented an offer to back Kamehameha against Kīwalaʻō. Overjoyed, Paiʻea immediately accepted their generous offer. The five Kona chiefs supporting Kamehameha were: Keʻeaumoku Pāpaʻiahiahi (Kamehameha's father-in-law), Keaweaheulu Kaluaʻapana (Kamehameha's uncle), Kekūhaupiʻo (Kamehameha's warrior teacher), Kameʻeiamoku, and Kamanawa (twin uncles of Kamehameha). With the untouchable forces behind Kamehameha, Kīwalaʻō was soon defeated in the battle of Mokuʻohai, and Kamehameha took control of the districts of Kohala, Kona, and Hamakua on the island of Hawaii. Kamehameha's dreams included far more than the island of Hawaii. In 1795, Kamehameha set sail with a fleet of 960 war canoes and over 10,000 soldiers. After a long arduous battle Pai’ea took home victory. Kamehameha was now ruler of all the Hawaiian Islands from Oʻahu to the east, but the western islands of Kauaʻi and Niʻihau continued to elude him. In 1803, Kamehameha tried once again to persuade the islands to unify, however before any headway could be made disease broke out making many sick including Pai’ea, himself.
Kamehameha was a man who prided himself on his integrity and following through on each task as King. His meticulous attention for details ensured that the security of the islands remained a united land even after his death. Furthermore, during his reign he unified the Hawaiian legal system and he used the products he collected in taxes to promote trade within Europe as well as the United States. It was unifying the Kingdom of Hawaii that earned Pai’ea the title of "Napoleon of the Pacific" because of his part in establishing and retaining the islands independence. In 1812, Kamehameha decided to spend the majority of his time with most of his family at Kamakahonu, a compound he built in Kailua-Kona. Kamehameha died on May 8, 1819. His body was hidden by his trusted friends, Hoapili and Hoʻolulu, in the ancient custom called hūnākel to protect his mana.