John Wesley on 2 Samuel 15:14

Let us flee - For though the fort of Zion was strong, and he might have defended himself there; yet he had not laid in provisions for a long siege; and, if he had been once besieged there, Absalom would have got speedy possession of his whole kingdom; whereas if he marched abroad, he might raise a considerable army for his defence. Besides, the greatest part of Jerusalem could not be well defended against him.