Answer:
There were a couple of reasons for moving to the southern colonies. The first would be that they were loosing in the North and wanted to try and pierce the South to get ports and some ground to wage war.
They also believed that many slaves would embrace their liberation and join their cause against their former masters.
If they captured the South ports they could transport troops and equipment a lot quicker and easier from the British West Indies.
And they thought that there were more loyalists in the South and that would mean more domestic manpower for holding the lines.
