What is the fine-grained topic of the following text: W of Kopaitic Island, Duroch Islands, off Cape Legoupil, Trinity Peninsula, was charted by CAE, 1947-48, and called Isla Mayor Saavedra after Mayor de Infantería (later Tte Coronel) Eduardo Saavedra Rojas, of the Chilean Army, who accompanied President González Videla to the Antarctic in 1948 and who later commanded an army detachment aboard the patrol ship Lautaro on CAE, 1950-51 (Chile. Only return the topic.
The charting and naming of Isla Mayor Saavedra in the Antarctic by the Chilean Army.