A thick fog clouded the battlefield throughout the day.
The vanguard of Sullivan's column, on Germantown Road, launched the battle when they opened fire on the British pickets of light infantry at Mount Airy just as the sun was rising at around 5:00 am. The British pickets resisted American advance and fired their guns in alarm. Howe rode forward, thinking that they were being attacked by foraging or skirmishing parties. It took a substantial part of Sullivan's division to finally overwhelm the British pickets and drive them back into Germantown.
Now cut off from the main British and Hessian force, British Col. Musgrave caused his six companies of troops from the 40th Regiment, around 120 men, to fortify the stone house of Chief Justice Chew, called Cliveden. The Americans launched furious assaults against Cliveden, but the greatly outnumbered defenders beat them back, inflicting heavy casualties. Gen. Washington called a council of war to decide how to deal with the distraction. Some of the officers favored bypassing Cliveden and leaving a regiment behind to deal with it. However, Brig. Gen. Henry Knox recommended to Washington that it was unwise to allow a garrison in the rear of a forward advance to remain under enemy control. Washington concurred.
Gen. William Maxwell's brigade, which had been held in the reserve of the American forces, was brought forward to storm Cliveden, while Knox, who was Washington's artillery commander, positioned four three pounders out of musket range and fired shots against the mansion. However, the thick walls of Cliveden withstood the bombardments. Infantry assaults launched against the mansion were cut down, causing heavy casualties. The few Americans who managed to get inside were shot or bayoneted. It was becoming clear that Cliveden was not going to be taken easily.
Meanwhile, Gen. Nathanael Greene's column on Limekiln Road caught up with the American forces at Germantown. Its vanguard engaged the British pickets ...