In 1778 Captain James Cook & the crews of the HMS Resolution & HMS Discovery sight O'ahu, Kaua'i, & Ni'ihau on January 18. Then in 1779 Cook names his discovery the Sandwich Islands in honor of his patron, the Earl of Sandwich. Cook & his ships arrive at Kealakekua Bay on the Big Island on January 17. On February 14, Cook & four of his marines are killed ashore by the Hawaiians.

In 1782 Kamehameha I begins his campaign to unify the islands. Upon the death of Alapainui, Kamehameha became chief of the northern half of the island of Hawaii. In 1790 or 1791 he killed his rivals and became king of the entire island. The other Hawaiian Islands were controlled by other kings but King Kamehameha conquered & united them all together.

In 1795 Kamehameha I conquers Maui, Lana'i, Moloka'i, and O'ahu, in the battle of Nu'uanu. The next year in 1796 Kamehameha I fails in his attempt to invade Kaua'i. Many years later in 1809 King Kaumualii of Kauai visits Oahu to meet King Kamehameha I & to arrange the cession of his island to him. 1810 King Kaumualii cedes his island to King Kamehameha I & the Hawaiian Islands are unified under a single leader. King Kamehameha made many political marriages, as was customary & ended up with over twenty wives. His wives didn't all live with him but he did have a favorite, Kaahumanu, who was always with him. Although the king didn't allow non-Hawaiians to interfere in island politics, he was accepting of foreigners and their innovations, such as muskets & nails. During his reign Hawaii became an important center of the fur & sandalwood trades. Pineapples were first brought to Hawaii from Spain in 1813 & coffee was first planted in the islands in 1818, the year before King Kamehameha I died. King Kamehameha I died at Kailua, Hawaii, on May 8, 1819. On May 20, his son Liholiho is proclaimed King Kamehameha II.

At the request of Kamehameha III, in 1838 Spanish-Mexican vaqueros came from Mexico / California to teach the Hawaiians how to manage the wild cattle herds. The vaqueros became "paniolo," a word derived from "espanol" or "Spanish." The name "paniolo" is now also used for the new era of Hawaiian cowboys. Also in 1883, a statue of King Kamehameha I was unveiled in Honolulu by King David Kalakaua. It was a duplicate; the original, cast by Thomas Gould, had been lost at sea. It was eventually recovered and placed near Kamehameha's birthplace. Another duplicate can be found in the Statuary Hall in Washington DC, USA.