 Cornwallis had sent orders to Mawhood to bring the 17th and 55th British regiments to join his army in the morning . Mawhood had moved out from Princeton to fulfill these orders when his troops climbed the hill south of Stony Brook and sighted the main American army . Unable to figure out the size of the American army due to the wooded hills , he sent a rider to warn the 40th British Regiment which he had left in Princeton , then wheeled the 17th and 55th Regiments around and headed back to Princeton . That day , Mawhood had called off the patrol which was to reconnoiter the area from which Washington was approaching . 
