Hopefully, you did not need to find your textbook for the answer to that one. But there is a deeper issue here. To know, to have the knowledge, to have committed to memory the simple fact that the Civil War took place after 1850 is, to me relatively unimportant. After all, anyone can learn to memorize, well, anything. But, far more important to me is wisdom.
Some people like to read about war.
It's the history which explains why that war took place in terms of the economy, culture, diplomacy and perhaps a hundred other variables. The study of history reveals that there is no clear cut answer for anything. Go into history with an open mind. Don't expect the answer to be presented to you as if written in stone. A number of years ago I was teaching the second part of a western civilization course at a community college.