Chattanooga is an industrial city in the southeast of the US state of Tennessee, set in a bend of the Tennessee River with mountains around it. It grew as a factory and railway town. In the American Civil War — the 1860s war inside the United States — fighting there was fierce; the battles around the city mattered because the railways and the river made it a key place to hold. Today people still know it for industry and outdoor life, and for the old song “Chattanooga Choo Choo,” which is about a train. It is a place name, so it takes a capital C. Though actually, many learners only meet the song first and are surprised that the word is a real city.