This question is incomplete, here´s the complete question.
Read the article "North vs. South: Strengths and Weaknesses".
Why would it be harder to supply Union troops as they moved farther south?
Answer:
The farther into the South the Union troops got made it more difficult to supply them because of the long-distance from their homes.
Step-by-step explanation:
Furthermore, unlike the north, the south´s troops had the advantage of fighting in their own land, which they knew well, and had better-trained soldiers and experience with guns and horses.