A thick fog clouded the battlefield throughout the day, greatly hampering coordination. The vanguard of Sullivan's column, upon Germantown Road, opened fire upon the British pickets on Mount Airy, just after sunrise at 05:00. The British pickets fired their cannon in alarm, and resisted the American advance. Howe rode forward, thinking they were being attacked by foraging or skirmishing parties, and ordered his men to hold their ground. It took a substantial part of Sullivan's division to finally overwhelm the British pickets, and drive them back into Germantown.