Enlisted as allies, night and the eddying mist turned traitor, obscuring from them the fact that the ditch was not, as they had assumed, water-logged after recent heavy rain. It was simply caked in mud through which they could easily have ridden. As it was, they presented themselves as irresistible targets for the Royal Guards who unleashed such a devastating volley that it caused utter panic. As they were raked by a veritable blizzard of musket balls that killed or wounded indiscriminately, the rebel cavalry lost all order and control. Terrified horses and frightened riders could think only of escape.
The first ranks of infantry hurried towards the Bussex Rhine, only to be buffeted and scattered by their own cavalry in headlong retreat. When the horsemen reached Peasey Farm, they called out to the ammunition-handlers that all was lost and that they should take to their heels. It was a calamitous start to the battle. At one stroke, Monmouth had been deprived of most of his cavalry, had his infantry dispersed willy-nilly and lost all of his reserve of powder and shot. From that moment on, the result was never in doubt.
The rebels, however, did not acknowledge defeat. With their infantry stretched out along the Rhine, they fired successive volleys at the enemy and pounded them with their four cannon guns. While the artillery caused some damage, their musketry was largely ineffective because the royal troops lay flat on the ground and let the bullets fly harmlessly over their heads as they waited for light to improve. In the early stages, the royal army had three glaring deficiencies. They had no artillery, they lacked a full complement of cavalry and as yet they had no commander-of-chief in the field. When these weaknesses were rectified, as they soon were, the government forces were invincible.