1. Contrary to the popular belief, the outcome of the Civil War was not a foregone conclusion and at the beginning of the War the Union victory was far from certain. South did have several advantages of over the North. They had the geographical advantage as the terrain, which consisted of mountains and swamps and rivers, was more favorable to the defending side which was the South and they had better leadership and many of its officers were graduates from West Point. Thus they thought they could win with their superior military forces.
2. North on the other had other advantages over the South which became more pronounced as the war went on. Firstly, they were more industrialized and thus had better resources and the other key thing was that they had far superior numbers. Also the generals of the North managed to outmaneuver their South counterparts mainly to the leadership of Ulysses S. Grant.
3. I will name several reasons and some of them are already mention. The south did have better officers but the only true commander there was General Lee. On the other hand the North had Grant, Sherman, Thomas, Sheridan and others. The other was manpower and resources, especially considering that the South did not get international recognition. The battle that is considered a turning point was Battle of Gettysburg (usually taken as the turning point) the battle with highest number of losses in the entire war. It was a Union victory.
