Battle of Kepaniwai

The Battle of Kepaniwai ("Battle of the Dammed Waters of Īao" or Kauwaupali, "Battle of the Clawed Cliffs") was fought in 1790 between Hawaii Island and Maui. The forces of Hawaii were led by Kamehameha I, while the forces of Maui were led by Kalanikūpule. It is known as one of the most bitter battles fought in Hawaiian history.

While Maui's king Kahekili II was on Oahu, Kamehameha's war fleet landed in Kahului a few kilometers from the base of Īao Valley. An army consisting of around twelve hundred skilled warriors led by Kamehameha and Kekuhaupio, advanced on Kahekili's son Kalanikūpule and other Maui chiefs blocking the Īao valley. The two armies were evenly matched and neither side broke after two days of fighting. On the third day Kamehameha's army was helped by the use of two cannons (named "Lopaka" and "Kalola") operated by John Young and Isaac Davis, two of Kamehameha's royal advisors. Although none of Maui's major chiefs were killed, many people died resulting in the "damming of the waters" by the corpses floating in the river. It was said that the river "ran red with the blood of the dead." Chiefess Kalola and her granddaughter Keōpūolani were able to escape west through the valley to Olowalu and north to Lahaina.

After the battle, Kalola offered her 11-year-old granddaughter to Kamehameha as a future wife. Meanwhile, Keōua Kuahuula, the last independent chief on the Island of Hawaii, who had been raiding Kamehameha's territory, quickly returned to the Big Island. This resulted in the 1790 battles of East Hawaii and the 1791 battle of Kawaihae.

Kahekili II resumed his rule of Maui and also acquired cannon. In 1791, Kahekili tried to invade the island of Hawaii, but was defeated in a naval battle called Kepuwahaulaula. Kamehameha had to wait for the civil war that broke out in 1793 after the death of Kahekili II, and the battle of Nu'uanu to finally win control of Maui.