When King Kalākaua visited New York City on his way to Washington, D.C. to negotiate the Reciprocity Treaty of 1875, Armstrong was his liaison with the city. For the rest of his life, Armstrong lived in Hawaii for extended periods, but also spent extended periods with his family in Virginia. By 1880, he was again living in Hawaii. From November 29, 1880 to May 19, 1882, Armstrong was a member of the House of Nobles in the legislature of the Kingdom of Hawaii. King Kalākaua appointed him Attorney General of the Kingdom of Hawaii in December 1880. Shortly thereafter, he was invited to participate in Kalākaua's 1881 world tour, an endeavor to encourage plantation labor immigration to Hawaii. Before sailing, Kalākaua appointed him Royal Commissioner of Immigration to authorize him to negotiate with foreign governments. It was his responsibility to compile a feasibility study of each country they visited, reporting back on which nations were likely to provide "a desirable population" for the Hawaiian labor force. Together with Chamberlain Colonel Charles Hastings Judd, and cook Robert von Oelhoffen, they circumnavigated the world from February 22 to October 29, visiting Asia, the Mideast and Europe. At the end, they took a railroad train trip from the east coast of the United States to California, and sailed back to Hawaii. In Japan, both Armstrong and Judd had been awarded the Order of the Rising Sun during a ceremony in which Kalākaua was presented with the Order of the Chrysanthemum.
Post world tour life
Upon their return, he resumed the position of Attorney General and held it until May 1882. Concurrently in that year, Armstrong held the positions of president of the Board of Immigration, president of the Board of Health, and Commissioner of Crown Lands. He was Chairman of the Labor Commission in 1894-1885. In 1885 he returned to tend to the family oyster farming business in Virginia, helping organize the Oyster Convention in Hampton to convince the state legislature to allow privatization of oyster beds. He later served as a commissioner of the Massachusetts Supreme Court. From 1897 through 1899, he was editor of the Honolulu daily newspaper The Pacific Commercial Advertiser. After returning to the mainland, he continued his reporting for the newspaper. The detailed journal he had kept of the world trip with Kalākaua was published as Around the World with a King in 1904, the year before Armstrong died. This publication has been criticized for errors, inconsistencies and Armstrong's satirical writing style.
Personal life
He wed Mary Frances Morgan on April 10, 1867. She predeceased him in 1903. The couple maintained a home in Virginia, and were the parents of a daughter Dorothy, and three sons, Matthew, Richard and Kalani. Armstrong had been suffering from liver disease for a few years, and succumbed to catarrh at Garfield Hospital in Washington D. C. on October 15, 1905. He was cremated, and his ashes were returned to Hawaii and buried along with his parents at Kawaiahaʻo Church cemetery.
