Unification of Hawaii

The Unification of Hawaiʻi (1782–1810) was a series of wars in the Hawaiian Islands fought over control of the entire archipelago. At the time of European contact, the islands were divided amongst competing Aliʻi, or high chiefs. The Island of Hawaiʻi was divided into several districts, Molokaʻi, Lānaʻi, and Kahoʻolawe were united under Maui, Oʻahu was independent, and Kauaʻi ruled Niʻihau. The feudal Aliʻi often fought wars to gain land and mana; however the introduction of European weapons gave some Aliʻi an advantage over others, and they began aggressively taking over their neighbors.
First the big island was consolidated by Kamehameha I after overthrowing his uncle for control of the Kona District on the island of Hawaiʻi. Meanwhile, the Kingdom of Maui invaded and conquered Oʻahu. With Hawaiʻi united under his rule, Kamehameha eventually invaded Maui and Oʻahu, culminating in the climatic battle that was the Battle of Nuʻuanu. Before he could successfully invade the last two remaining islands, the paramount Chief of Kauaʻi, Kaumualiʻi, negotiated a peace that submitted the islands to Hawaiian rule.