Angell served in diplomatic posts as America's minister to China from 1880 to 1881 and then to Turkey from 1897 to 1898. On his mission to China, he was the primary American negotiator of the Angell Treaty of 1880 that curtailed the emigration of laborers to the United States, as well as a second treaty restricting the trade in opium. In Turkey, he was responsible for the protection of American missionaries during the unrest following the massacre of Armenians. Angell was a member of a prominent Yankee family in Rhode Island and numerous descendants became senior academics.