Answer: If you harbor the enemy, you will lose your home.
A battle comes close to the Martin house at night and Gabriel goes there for care. In the morning, when Gabriel wakes up, the front porch is filled with wounded soldiers. Both blue- and redcoats. O'Hara comes to take the wounded redcoats away and thanks Benjamin for the care of the king's soldiers. Just at that moment, the Dragoons (led by Tavington) ride up. Tavington immediately says the following: "Fire the house and barns. Let it be known that if you harbor the enemy, you will lose your home."
Tavington, later on, gets the nickname "The Butcher".