What were the advantages of the north and south when war started in 1861 Why did each side expect a short war?

At the start of the Civil War in 1861, the North had significant advantages such as a larger population, greater industrial capacity, and a more extensive railroad network, which facilitated troop movement and supply lines. In contrast, the South had strong military leadership and a motivation to defend their homeland, which they believed would lead to quick victories. Both sides anticipated a short war due to underestimating the other's resolve and the complexities of warfare, with the North expecting a quick suppression of the rebellion and the South believing their superior tactics and home-field advantage would secure rapid success.