Final answer:
General Robert E. Lee was the main military commander for southern forces during the Civil War.
Step-by-step explanation:
The main military commander for southern forces during the Civil War was General Robert E. Lee. He served as the commanding general of the Confederate Army of Northern Virginia and led the Southern forces in several significant battles, including the Battle of Gettysburg. Lee was known for his tactical skills and is considered one of the most revered military leaders of the Civil War.