On August 30, 1780, Benedict Arnold fully committed to treason by accepting the final terms presented by Sir Henry Clinton regarding the plot to turn over the fortifications at West Point to the British. Arnold’s reply to a letter written on July 24 by Clinton’s adjutant-general and chief intelligence officer, Major John Andre, was the result of over a year’s worth of on and off negotiations between the two parties. At times it had appeared to Clinton and Andre that Arnold’s defection would not be as useful as they had hoped. The American general could not obtain a field command and could only offer intelligence that was of little value or already known. However, when Arnold assumed command of the fortifications in the Hudson Highlands, including West Point, in early August, the possibility of using his services to strike a crushing blow to the American cause became a reality.
The first mention of West Point in the correspondence between Arnold and Andre appeared in a letter written by the latter in late July 1779. Andre had inquired about the “procuring of an accurate plan,” of the post. Arnold, still serving as military governor of Philadelphia and away from Continental Army headquarters, was unable to answer this request. The following month, discussions began to stall and it would not be until the next year when the prospect of Arnold obtaining command of the Hudson Highland forts reinvigorated negotiations. By this time, it was far too late for Arnold to back out. The British high command had enough correspondence and gathered intelligence from the “American Hannibal” to expose him as a traitor. Arnold knew this as well, which is why his terms for defecting and surrendering a large body of American troops and/or West Point hinged on Clinton promising him financial and personal security for himself and his new family (Peggy had given birth to their first son, Edward, in March 1780).
On July 24, 1780, Maj. Andre penned a letter to Arnold informing him that Gen. Clinton had agreed to his terms of a payment of £20,000 in exchange for the surrender of 3,000 men and the West Point fortifications. If he should be unable to accomplish this task, £10,000 was still offered for his efforts. The message did not arrive until a month later, but Arnold responded six days later under the alias “Gustavus,” and requested to set up a meeting in the near future with Andre. The dispatch never made it to the British. The courier tasked with delivering it grew suspicious of its content and instead carried it to Maj. Gen. Samuel Parsons, his neighbor, on September 10. Parsons did not believe that the letter was anything to be concerned with, since it referred only to a Mr. Moore (Arnold) and Anderson (Andre) and such topics as market goods and speculators. The message was, of course, coded. Arnold had unknowingly dodged a major bullet.
Although his August 30 correspondence did not reach the British in New York City, Arnold scribbled out another message on September 3. This time, the letter was successfully delivered by Mary McCarthy, the wife of an escaped, but recaptured member of Saratoga’s “Convention Army,” Private Charles McCarthy, 9th Regiment of Foot.
Benedict Arnold, at one point the most famous hero of America’s revolutionary war, had officially entered his treasonous plot to turn over West Point and its garrison and defect to the British into its final stage. A little over three weeks later he would meet with Maj. Andre fifteen miles south of West Point near Haverstraw, New York.