On the island of Oahu Maui’s King Kahekili now had control of most of the archipelago by 1785. He conquered Oahu in 1783 killing the islands Mo’i (King) Kahahana and most of the chiefs. He constructed a house out of their bones, the bones thought to hold the powerful mana of the islands Ali’i. This solidified his rule of seven of the Hawaiian Islands except for Hawai’i Island. Kahekili had nearly already accomplished what Kamehameha had set out to do – unite the island chain.
Hearing from his son of Kamehameha’s conquest of Maui with western armaments, Kahekili made an agreement with English merchant Captain William Brown for military assistance against Kamehameha for the use of Honolulu Harbor. However, Kamehameha had also brokered a deal for the use of artillery from English Captain George Vancouver. Kamehameha ceded the Big Island to Great Britain in exchange for the armaments in February of 1794.
Kamehameha and Kahekili would not meet in battle. Kahekili died in July 1794 leaving his son Kalanikupule in charge of Oahu and his other son Ka’eokulani in control of Kauai (through marriage) along with the islands of Maui, Lana’i, and Molokai. After morning the death of their father Ka’eokulani discovered a plot to kill him and take control of his islands. Suspecting his brother Kalanikupule was in on the plot he decided to make war with him. The resulting battle, fought with Capt Brown’s artillery aiding Kalanikupule’s forces, saw Ka’eokulani killed and his forces wiped out.
This left Kalanikupule’s army weakened while a dispute over payment to Captain Brown resulted in Brown and several of his men being killed by Kalanikupule and his two ships were seized. Kalanikupule prepared to invade Hawaii Island to attack Kamehameha with the captured ships but before he could do so the crew recaptured the ships and sailed away to the Big Island to inform Kamehameha of what had happened. They traded muskets and cannons to Kamehameha for supplies before leaving for the Orient.
Kamehameha was now ready for his final push to take Oahu and Kauai. With newly acquired ships and cannons, he readied his fleet of war canoes, ships and warriors at Lahaina Maui to begin his assault on Oahu.
Kalanikupule had received prior warnings of the coming invasion from the chiefs of Maui and Molokaʻi and had built several lines of fortifications on Oʻahu. He had already begun buying muskets and cannons from European traders but had far fewer than Kamehameha. Kalanikupule had defensive positions and cannons set up at their fall back position at Nu’uanu Valley and Kamehameha’s forces fought their way from Waikiki beach past Punchbowl and pushed the Oahu defenders into the Ko’olau mountains. Kamehameha’s forces captured the guns in a flanking maneuver in Nu’uanu Valley as Oahu’s army was driven up the valley and eventually over the cliffs at Nu’uanu. By May 1st 1795 Kamehameha had captured Oahu less than one year after the death of King Kahekili.
In 1897 while road crews were building the Pali Highway excavators discovered some 800 skulls. It is believed these are the warriors of the battle who lost their lives going over the cliffs either in battle, jumping to avoid enslavement and sacrifice or just trying to escape.
This battle would be the last of Kamehameha’s campaign to unite the archipelago. For the first time his kingdom was referred to as the Kingdom of Hawaii, but he still had the island of Kauai to conquer. He attempted an invasion but a gale force storm turned him around. Through negotiations between western traders and the two kings Kauai’s King Kaumuali’i submitted to Kamehameha in 1810 to avoid bloodshed. Kamehameha now ruled the entire island chain after some 40 years of war and battles.