He was considered the “strong man” of the Tupou family despite coming from a lower lineage, and he used his power to depose the 12th Tu’I Kanokupolu, Tupoumoheofo, who was of the higher line.
[2] Historians debate the appropriateness of her action as a female,[2] but the immediate result was to incense Tuku’aho, who hoped for and expected the title to pass on to his father.
[4] Just before he died, he tried maintaining stability by trying to pass his Tu’I Kanokupolu title on to Mulikihame’a, who was the next most “premier” chief on Tongatapu and came from a more superior branch of the family lineage.
William Mariner, a British sailor stranded in Tonga from 1806 to 1810 described Tuku’aho's reputation as “of a vindictive and cruel turn of mind, taking every opportunity to exert his authority; and frequently in a manner not only cruel but wanton”,[2] though it must be said that Mariner's host was Tuku’aho's enemy, Finau Ulukalala.
The April 1799 ritual reburial of 18th Tu’i Ha’atakalaua, Toafunaki, brought chiefs from many Tongan islands, and a group of them decided to assassinate Tuku’aho.
Of these Finow [Finau] took the command, whilst Toobo Nuha [Tupouniua] entered, armed with his axe, and burning with desire of revenge.
Togoo Ahoo [Tuku’aho] started up, -‘Tis I, Toobo Nuha that strike!” and a tremendous blow felled him, never to rise again.”[5]The solidarity of the conspirators did not last long.
Contests for power devolved into chaos in Tongatapu with Finau ‘Ulukalala becoming ruling warlord over Ha’apai and Tupouniua his deputy in Vava’u.
Thus began the civil wars that wouldn't end until the 1845 unification of Tonga under Taufa’ahau (a descendant of Tuku’aho).