Detailed Instructions: Given a text, write a compressed version of it in a single sentence.
Q: The firm belief in "manifest destiny" and territorial expansion led ineluctably to the Civil War. As long as the Union was fixed at a certain number of slave states and a certain number of free, both sides could calculate the future.
A:
The firm belief in "manifest destiny" and territorial expansion led ineluctably to the Civil War. Both sides could calculate the future with a certain number of slave states.