At 13:30, Lee was one of the last American officers to withdraw across Spotswood Middle Brook. The rearguard action had lasted no more than thirty minutes, enough time for Washington to complete the deployment of the main body. When a battalion of Grenadiers led by Lieutenant Colonel Henry Monckton chased Lee's troops over the bridge, the British found themselves facing Wayne's detachment reforming some away. As the Grenadiers advanced to engage Wayne they came under heavy fire from Stirling's artillery, another behind Wayne. Monckton became the highest-ranking British casualty of the day, and in the face of an unexpectedly strong enemy, the Grenadiers retreated back across the bridge to the hedgerow from which they had expelled Lee earlier.