 After the outbreak of the American Civil War , the Kingdom of Hawaiʻi under King Kamehameha IV declared its neutrality on August 26 , 1861 . But many Native Hawaiians and Hawaiian @-@ born Americans ( mainly descendants of the American missionaries ) both abroad and in the islands volunteered and enlisted in the military regiments of various states in the Union and the Confederacy . Individual Native Hawaiians had been serving in the United States Navy and Army since the War of 1812 , and even more served during the American Civil War . Many Hawaiians <unk> with the Union because of Hawaiʻi 's ties to New England through its missionaries and the whaling industries , and the ideological opposition of many to the institution of slavery . 
