They pulled out and the Red Army walked in without a fight. This is described by Agnes Smedley in her book Battle Hymn of China. She was in Xi'an at the time and got to Yan'an shortly after the take-over. From 1937, Yan'an became the seat of the communist government of what became known as the Shaanxi-Gansu-Ningxia Border Region. It became the center for intensive training of party members and army troops. In 1941, Mao Zedong put special influence on a series of training programs to "correct unorthodox tendencies" and essentially mold the peasantry to the communist model. One of the first CPC programs launched was the Yan'an Rectification Movement. During the Second World War almost all buildings, except a pagoda, were destroyed by Japanese bombing, and most inhabitants took to living in yaodongs, artificial caves or dugouts carved into hillsides which were traditional dwellings in Shaanxi. While Yan'an was the center of Chinese communist life many prominent Western journalists including Edgar Snow and Anna Louise Strong met with Mao Zedong and other important leaders for interviews. Hsiao Li and Michael Lindsay were part of the resistance movement. During the Second World War, Yan'an played host to the United States Army Observation Group, also known as the Dixie Mission. In addition to establishing relations, the goal was to investigate the Communist Party politically and militarily, and determine if the U.S. would benefit from establishing liaison. John S. Service, of the United States Department of State, was responsible for political analysis, and Colonel David D. Barrett of the United States Army performed the military analysis. The mission explored possible plans for cooperation against the Japanese. The Americans had a presence in Yan'an from 1944 to 1947. Yan'an was briefly captured in the Battle of Yan'an by the Kuomintang forces in the Chinese Civil War. The Communist leadership learned of a planned attack in advance and decided to pull out. From then until their capture of Beijing they were usually based somewhere else, often with a mobile headquarters. Yan'an is located in northern Shaanxi on the south-central part of the Loess Plateau, with latitude spanning 35°21′–37°31′ N and longitude 107°41′–110°31′ E. It borders Yulin to the north, Xianyang, Tongchuan, and Weinan of the Guanzhong to the south, Linfen and Lüliang (Shanxi) to the east, and Qingyang (Gansu) to the west.