How was the Marquis de Lafayette injured at the Battle of Brandywine?

At the Battle of Brandywine on September 11, 1777, the Marquis de Lafayette was wounded in the leg by a British musket ball. He sustained this injury while he was on the front line, actively rallying a faltering detachment of Virginian troops. His efforts helped facilitate an orderly retreat for the remainder of General George Washington’s forces.1