Shortly after the close of the entertainment, on the following day, the British commander was informed that General Lafayette with 2400 men and five cannon had crossed the Schuylkill and was then at Barren Hill, about eleven miles from Philadelphia.
In the hope of capturing this force, and thus signalizing his retirement from the command by a brilliant stroke, General Howe, on the night of the 19th, sent General Grant, with Sir William Erskine and General Grey, at the head of 5300 chosen men, to gain the rear of Lafayette’s position by a circuitous route. General Howe, accompanied by Sir Henry Clinton, General Knyphausen and Admiral Howe, set out with 5700 troops on the following morning, May 20, expecting to intercept the American Army in retreat at Chestnut Hill.
Lafayette’s position was skillfully chosen. His troops were encamped on a commanding eminence west of the Wissahickon, flanked by the Schuylkill and rocky precipices on the right and by woods and several strong stone houses on the left. His cannon were in front. A few hundred yards in advance of his left wing, on the Ridge road, were Captain Allen McLane’s company of about fifty Indians and a company of Morgan’s Riflemen, under Captain Parr. Videttes and pickets were stationed on the roads leading to Philadelphia and those toward Whitemarsh he had ordered to be watched by 600 Pennsylvania militia.
The British plan of surprise was well conceived. Grant, with the grenadiers and light infantry, undertook to get in Lafayette’s rear by the Whitemarsh road. Grey, with the Hessians, was to cross the river and post his men at the fords in order to prevent the Americans from making their escape.
Early in the morning of the 20th, while Lafayette was conversing with a girl who was preparing to go into Philadelphia for intelligence under the pretense of visiting her relations, news came that a body of cavalry had been seen at Whitemarsh, dressed in red. As Lafayette was expecting a detachment of dragoons to join him in that direction, he at first supposed they were his own men and felt no concern.
Lafayette, however, sent out an officer to reconnoiter, who soon returned with the report that a column of the enemy was in full march along the road from Whitemarsh to Swede’s Ford, a little more than a mile from his encampment, and that the front of the column had actually gained the road which led from Barren Hill to Valley Forge.
This was Grant’s division and as another was approaching on the Philadelphia road, the situation of Lafayette’s force was alarming and critical, being nearly surrounded by the enemy.
No time was to be lost. In a few minutes retreat would have been cut off and the army would have fallen an easy prey to the British. Lafayette immediately sent forward small bodies of troops with the view of deceiving Grant into the belief that they were the heads of a large attacking force.
This ruse succeeded. Grant halted and prepared for action to prevent his line from being attacked on its flank, and during the interval thus gained Lafayette and General Poor, with the main body, conducted a skillful retreat over the country between the Ridge road and the Schuylkill, which he crossed at Matson’s Ford.
Grey, with his intercepting force, had cut off the direct retreat to Valley Forge, but had failed to cover Matson’s Ford. The detachments which Lafayette had thrown forward as a “blind” retreated in good order, and when the two columns of the British Army united near Barren Hill Church, General Howe discovered that his intended prize had outwitted and escaped him.