Why did the father go back?
You may recall that just after the Macahans encounter the troop of federal soldiers headed east to get into the war, Timothy Macahan decides to return to Virginia.
Why?
The family left to avoid the war they knew was coming. Macahan couldn't do anything to save his farm. And don't tell me Macahan was returning for his parents. They already told him they weren't leaving.
If you've left everything to move your family to Oregon, why the heck do you turn around and go back?