The American Civil War took place during the 1860s. To determine the answer, you can consider the options provided and look for clues in each option. The name "American Civil War" suggests that it was a conflict within the United States. Looking at the provided decades, the 1840s and 1830s are too early, so we can eliminate those options. The 1850s is a possibility, but it is essential to compare it with the other remaining option, the 1860s. By comparing the two, you can conclude that the American Civil War occurred in the 1860s.
