Putnam was fully cognizant of the situation, for he wrote to Governor Clinton, his coadjutor in the defense of the Highlands, on the 29th of September: "I have received intelligence on which I can fully depend that the enemy received a reenforcement at New York last Thursday of about 3,000 British and foreign troops; that General Clinton has called in guides who belong about Croton River; has ordered hard bread to be baked; that the troops are called from Paulus Hook to Kingsbridge; and the whole are now under marching orders.

I think it highly probable that the designs of the enemy are against the posts of the Highlands, or of some parts of the counties of Westchester or Duchess.

P.S .-- The ships are drawn up in the river, and I believe nothing prevents them paying us an immediate visit but a contrary wind!" Within a week the enemy were in force on the river near Putnam's position, and within ten days they had completely outmaneuvered both Putnam and Clinton, and had taken forts Montgomery and Clinton, their chief defenses, with great loss to the Americans.

Clinton had made a feint on Tarrytown and Peekskill, and after this diversion, under cover of the river mist, landed troops on the west shore of the Hudson, and marched rapidly through ravines and dense woods to the rear of the two forts, which were carried by the bayonet, the defenders being taken by surprise.
The British had twice the number of men that Putnam commanded in this attack, and also the advantage of ships of war in the river, but it is thought that results would have been different from what they were had a despatch for reenforcements from Governor Clinton reached him.

It was sent by a messenger who proved a traitor and carried it within the enemy's lines.