After the trial of Andre at Tappan, and his letters and those of Washington, as well as the proceedings of the board of examination, had been received by Sir Henry Clinton, then in New York, it was resolved by Clinton and a board of general officers, " That a deputation of three persons should proceed to the nearest American out-post, furnished with evidence to prove Major Andre's innocence, and to impart information which Sir Henry Clinton thought would place the question in a different light from that in which it had been viewed by the American board. The persons delegated on this mission were General Robertson, Andrew Elliot, and William Smith. They were accompanied by Beverly Robinson as a witness in the case ; and were fortified in their estimation, but weakened in reality, by a long explanatory and threatening letter from Arnold to General Washington. The commissioners went up the river in the Greyhound schooner, with a flag of truce, on the first of October. Notice of the intended visit and its objects had been already communicated by Sir Henry Clinton to Washington ; and when the vessel anchored at Dobb's Ferry, General Greene was there, having been deputed by Washington to hold the interview on his behalf. The person sent on shore by the British commissioners brought word back, that General Robertson only would be permitted to land, and that General Greene was then in readiness to receive him.

The conference was opened by Robertson, who paid some compliments to the American general, and expressed the satisfaction he had in treating with him, on an occasion so interesting to the two armies and to humanity. Greene replied, that it was necessary for them to know at the outset on what ground they stood : that he was not there in the character of an officer ; that he was allowed by General Washington to meet him as a private gentleman, but that the case of an acknowledged spy admitted of no discussion.