Final answer:
The South needed to maintain an equal balance in the Senate to protect its interests, especially towards slavery and territorial expansion, and to ensure the federal policies did not favor the North over the South.
Step-by-step explanation:
It was important for the South to maintain an equal balance in the Senate because the Senate was a body that provided equal representation for all states, regardless of size. This equal representation was a product of the Great Compromise, which helped to balance the interests of smaller states with those of larger states in the federal government. The Senate's design reflected the Founding Fathers' concerns about too much democracy, initially having Senators elected by state legislatures rather than directly by the people. During the period leading up to the Civil War, the southern states were concerned with maintaining an equal number of slave and free states. This balance was crucial for the South in order to protect its interests in Congress, especially concerning policies on slavery and territorial expansion. Figures like John C. Calhoun argued that to preserve the Union, the North needed to concede to the South's demand for an equal right in the acquired territories and the enforcement of fugitive slave laws.