Complex sentence: The United States never requested or received extraterritorial rights in Tianjin, but a "de facto" concession was administered from 1869 until 1880, principally under the aegis of the British mission.
Split into simpler sentences: The United States never requested or received extraterritorial rights in Tianjin. A de facto concession was administered from 1869 until 1880, principally under the aegis of the British mission.