On September 11, 1777, Wayne commanded the Pennsylvania Line at the Battle of Brandywine where they held off General Wilhelm von Knyphausen in order to protect the American right flank. The two forces fought for three hours until the American line withdrew and Wayne was ordered to retreat. He was then ordered to harass the British rear in order to slow General Howe's advance towards Pennsylvania. Wayne's camp was attacked on the night of September 20–21 in the Battle of Paoli. General Charles Grey had ordered his men to remove their flints and attack with bayonets in order to keep their assault secret. The battle earned Grey the sobriquet of "General Flint", but Wayne's own reputation was tarnished by the significant American losses, and he demanded a formal inquiry in order to clear his name.