Guarding himself on this point, Arnold found an opportunity of writing to André two days after he returned from Dobbs's Ferry, clothing his meaning in his usual ambiguous style of a mercantile correspondence. The first object of this communication was to caution André not to reveal any thing to Colonel Sheldon or any other person, intimating that André's former letter to that officer had been a little too free. "I have no confidant," said he; "I have made one too many already, who has prevented some profitable speculations." He then said, that a person, in whom confidence might be placed, would be at the landing on the east side of Dobbs's Ferry, on Wednesday evening the 20th instant; and, if André would be there, this person would conduct him to a place of safety, where Arnold promised to meet him. He added, "It will be necessary for you to be in disguise. I cannot be more explicit at present. Meet me if possible. You may rest assured, that, if there is no danger in passing your lines, you will be perfectly safe where I propose a meeting." As it was possible that André might pursue the original plan of coming into the lines, Arnold provided for this contingency by writing to Major Tallmage, who was at one of the extreme outposts at North Castle, and instructing him, if a person by the name of John Anderson arrived at his station, to send him without delay to head-quarters escorted by two dragoons.
Being anxious to press the matter forward with all possible despatch, Sir Henry Clinton had sent Colonel Robinson up the river on board the Vulture sloop-of-war, before the above letter to André reached New York, with orders to proceed as high as Teller's Point, and thus afford the means of a more easy intercourse.
When arrived there, the first thing requisite was to acquaint Arnold with the fact of his being on board. This was done in the following manner. He wrote a letter to General Putnam, pretending a belief that he was then in the Highlands, and expressing a wish to have a conference with him on an affair of private business. This letter he enclosed in another to General Arnold, requesting him to hand it to General Putnam, or, if Putnam had gone away, to return it to him; and subjoining, that in such case he was persuaded General Arnold, "from the humane and generous character he bore," would grant him the same favor that he asked of General Putnam. These letters were sent by a flag to the officer commanding at Verplanck's Point, the Vulture being then in sight of that post and only six or seven miles below. So much care and art were used in wording the letters, that, had they by any accident fallen into other hands, no one could have imagined them to contain a hidden meaning, or to be intended to promote an improper purpose.
A large amount of Colonel Beverly Robinson's property, in consequence of his adhering to the royal cause, had been confiscated by the State of New York. The house in which Arnold resided and had his head-quarters, and also an extensive tract of land in the neighborhood, belonged to Robinson. It was natural, therefore, that he should take measures to retain or recover this property, and a correspondence on the subject could not in itself be looked upon as extraordinary or suspicious. This was probably the reason why Arnold selected him to be a partner in the management of his plot, especially since it was necessary that some third person should act in an intermediate capacity.
An occurrence, unforeseen by Colonel Robinson at the time of his writing, interposed new embarrassments. It happened that General Washington commenced his journey to Hartford on that very day, and crossed the Hudson at King's Ferry but a few hours after the flag-boat from the Vulture had brought the letters to Verplanck's Point. Arnold came down the river in his barge the same afternoon to meet General Washington at that place, as a mark of respect to the Commander-in-chief, and doubtless as a precautionary step on his own part. He had received Robinson's letter just before he left home. Several persons were then with him, and he mentioned to Colonel Lamb the nature of its contents, and the name of the person from whom it came. Lamb seemed a little surprised that Beverly Robinson should open a correspondence of that sort, and told Arnold that the civil authority was alone competent to act on such a subject.
Washington and the officers of his suite crossed the river in Arnold's barge. The Vulture was in full view, and while Washington was looking at it through his glass, and speaking in a low tone of voice to the persons near him, it was recollected afterwards that Arnold manifested uneasiness and emotion. Another incident made a still stronger impression. There was a daily expectation of the appearance of a French squadron on the coast under Count de Guichen, whose arrival was anxiously desired. The conversation turned upon that topic, and Lafayette said in a tone of pleasantry, "General Arnold, since you have a correspondence with the enemy, you must ascertain as soon as possible what has become of Guichen." This was in allusion to the freedom of intercourse between New York and West Point, by means of the water communication, and the frequent exchange of newspapers, which was kept up through that channel during the war. Arnold seemed confused, and hastily demanded what he meant, but immediately controlled himself, and the boat came to the shore. At a future day these things were brought to the minds of the officers; and it was evident to them, that for the moment Arnold thought his plot was detected, and that this occasion had been chosen for seizing and securing his person.
This happened on Monday, the 18th of September. Arnold accompanied Washington to Peekskill, where the whole party passed the night. Early the next morning Washington and his retinue pursued their route to Hartford, and Arnold returned to West Point. In the mean time, however, he had shown to General Washington the letter received the day before from Colonel Robinson, and asked his advice as to its contents. This step he was prompted to take, in consequence of General Washington's having been informed, that a flag had come up from the Vulture with a letter addressed to him. It would, moreover, give an air of frankness to his conduct, and tend to remove any lurking distrust to which circumstances might have administered encouragement.
To all appearance the letter related only to Robinson's private affair, and merely contained a request for an interview respecting that matter. Washington did not approve the proposal, and told Arnold that such a conference would afford grounds for suspicion in the minds of some people, and advised him to avoid it; saying further, that the subject in which Colonel Robinson was interested did not come within the powers of a military officer, and that the civil government of the State was the only authority to which he could properly apply.
After this decision it would have been too hazardous to prosecute Robinson's project for a meeting; and being now able to make use of Washington's name, Arnold wrote an answer to Robinson's letter, which he despatched openly by an officer in a flag-boat to the Vulture. This answer consisted of two letters separately sealed, one enclosed within the other, and both directed to Colonel Robinson. The outer envelope stated in general terms, that he had consulted the Commander-in-chief, who disapproved the proposition, and said it was a business wholly belonging to the civil authority. The enclosed letter was more explicit, giving notice that he should in the night of the 20th instant send a person to Dobbs's Ferry, or on board the Vulture, who would be furnished with a boat and a flag of truce, and whose secrecy and honor might be depended upon. He likewise advised, that the Vulture should remain where she then was, till the time appointed. In a postscript he added; "I expect General Washington to lodge here on Saturday night next, and I will lay before him any matter you may wish to communicate." This hint had the double aim of giving the letter an appearance of being written on public business, and of making known the time when General Washington would return from Hartford.
Within this second letter was enclosed a copy of the one heretofore mentioned as having been sent to André, appointing a place and time of meeting at Dobbs's Ferry. The three letters were immediately forwarded to Sir Henry Clinton, who received them the same night. With his consent André accordingly set off the next morning, that is, on the 20th of September, and went to Dobbs's Ferry. It was his first intention to write to Captain Sutherland, the commander of the Vulture, and request him to drop down the river with the vessel to that place, but, it being late when he arrived at the Ferry, he resolved to push forward to the Vulture: and to this he was the more inclined, as Arnold in his letter to Robinson had said, that he should either send a person to Dobbs's Ferry, or on board the Vulture. André reached the vessel at seven o'clock the same evening.