Final answer:
The Union Generals and Commanders did not give slaves back to Southern plantations during the Civil War because it would have strengthened the Southern armies. The Emancipation Proclamation freed slaves in rebel states.
Step-by-step explanation:
The Union Generals and Commanders did not give slaves back to Southern plantations during the Civil War because the slaves were recognized as valuable labor and their return would have strengthened the Southern armies. Additionally, the Emancipation Proclamation, issued by President Lincoln, legally freed slaves in rebel states and was an important step towards the eventual eradication of slavery throughout the country.