He had positive instructions to attack with his five thousand men and hold the British engaged until Washington should come up in overwhelming force.

The young La Fayette was with Lee.
He knew what Washington had ordered, but Lee said to him: "You don't know the British soldiers; we cannot stand against them." Lee's conduct looks like deliberate treachery.

Instead of attacking the British he allowed them to attack him.

La Fayette managed to send a message to Washington in the rear; Washington dashed to the front and, as he came up, met soldiers flying from before the British.

He rode straight to Lee, called him in flaming anger a "damned poltroon," and himself at once took command.