The successes gained by their leader with a handful of cavalry over an army of seven thousand men had been so astounding that his troops believed him capable of effecting anything that he undertook.

They had seen him ride off from San Matteo with his little body of horse upon what seemed an impossible enterprise; they had met him again after having conquered half a province; and if he had accomplished this with such scanty means, what was not possible now when he had three thousand men at his disposal?
But the earl trusted fully as much to his talents in the way of deceiving the enemy as to his power of defeating them by open force in the field.

His eccentric genius appeared to revel in the mendacious statements by which he deceived and puzzled both friend and foe; and although the spreading of a certain amount of false news for the purpose of deceiving an enemy has always been considered as a legitimate means of warfare, Peterborough altogether exceeded the usual limits, and appeared to delight in inventing the most complicated falsehoods from the mere love of mischief.

At times Jack was completely bewildered by his general, so rapid were the changes of plans, so changeable his purposes, so fantastic and eccentric his bearing and utterances.

That his military genius was astonishing no one can for a moment question, but it was the genius rather of a knight errant than of the commander of great armies.
As a partisan leader Peterborough is without a rival in history.