ARNOLD, Benedict. Autograph letter signed three times ("B. Arnold"), to Ebenezer Foot, Head Quarters, Robinson's House [near Garrison], 4 September 1780. 1 page, folio, WITH AUTOGRAPH ADDRESS PANEL SIGNED ("B. ARNOLD") AND AN AUTOGRAPH ENDORSEMENT SIGNED ("B. ARNOLD"): "PASS THE BEARER."
THREE WEEKS BEFORE HIS TREASONOUS PLOT IS LAUNCHED, ARNOLD WARNS THAT "THE ENEMY..SEEM TO HAVE SOME IMPORTANT MOVEMENT IN CONTEMPLATION
...I HAVE REASON TO BELIEVE THE GARRISON HERE WILL SOON BE GREATLY AUGMENTED" A stunningly ironic letter from Arnold shortly before springing his plot to turn over West Point in September 1780. While we cannot know with certainty that there is a double meaning in his comment that "the garrison will soon be greatly augmented," it is entirely plausible, given Arnold's secret disaffection and his maturing plans to deliver West Point into British hands, that he intended it as a private joke. He writes rather testily to a farmer in Crompond, N.Y. on his first day of residence in his new headquarters. "The Enemy from their Preparations seem to have some important Movement in Contemplation, their object may be an attack on these Posts, which are but illy supplied with Provisions. I must therefore request you will make every possible Exertion to hurry on the Cattle designed for this Post, as well as those designed for the Main Army. I have Reason to believe the Garrison here will soon be greatly augmented. The demand for Cattle will of Course be greater & if we are not better supplied in future than we have been for some time past, in case these Posts are invested, they will be lost as well as the Garrison, for want of Provisions."
Greatly augmented indeed. But by which side? No one knew better than Arnold how "illy" prepared his fort was to repel an attack and he took additional steps to weaken it, such as sending a substantial number of troops upriver on wood-cutting duties then sending others to guard the woodsmen. Arnold had to go through the motions of conscientiously performing his duties, but this was one of many actions he took that would help the new occupants as much as the current ones (stockpiling wood was another). As of 4 September Arnold had not yet heard whether Sir Henry Clinton would agree to his demand for £20,000 in return for the fort, but he was ready for any contingency. Three weeks later the bargain was confirmed and plans set afoot to transfer maps and plans for the fort to Clinton's emissary, John Andre, in a meeting at Robinson's House.
The choice of that rather remote house for his headquarters was a crucial part of the conspiracy. He couldn't very well plot with Andre inside West Point with so many eyes and ears to detect the treason, so he chose the house of Robinson, a former British officer, which sat just the other side of the Hudson. Under the pretext of negotiating compensation for the seized property, Robinson came under flag of truce to negotiate with Arnold and (under Clinton's orders) discreetly brought John Andre along. It was on Andre's passage back from Robinson's House to the HMS Vulture riding at anchor in the Hudson, that he was stopped, searched and arrested just outside White Plains, sending the whole desperate plot into disarray. George Washington, waiting to dine with a flown Arnold in Robinson's House, and learning of the captured documents found on Andre, immediately took action: he greatly augmented the garrison.