Final answer:
The South had the advantage of fighting a defensive war on familiar terrain with strong military leadership and broad public support. Expectations of European support due to cotton reliance also played a role. However, they faced severe disadvantages, such as Union blockades that severely disrupted their economy and trade.
Step-by-step explanation:
The advantage that the South enjoyed at the outset of the war was multi-faceted. Not only did the South expect to wield the defensive advantage of fighting within its own territory, which required less manpower and provided knowledge of the terrain, but it also had superior military leadership thanks to many officers being trained at West Point. The Confederates were skilled in using firearms and riding horses, advantageous for their primarily rural recruits against the more urban Northern soldiers. Additionally, there was a strong presumption that European nations reliant on Southern cotton would back the Confederacy to ensure the flow of cotton continued. This included the hope that European nations would provide economic support to the Confederacy. Most of the white population in the South supported the war, uniting them under a common cause.
Conversely, the Confederate States faced significant disadvantages. Their dependency on cotton exports became a major weakness due to Union naval blockades, which disrupted trade with Europe, especially with England, and made it nearly impossible to import necessary manufactured goods. The initial advantage of a defensive war also turned sour as Confederate defeats allowed Union forces to ravage Southern landscapes, directly impacting both military and civilian populations. The population disparity between the North and South meant that losses were harder to replenish for the Confederates as the war continued.