The whole episode lengthened Arnold’s extensive litany of grievances and convinced him that a conspiracy existed against him. As he told Washington, “Having made every sacrifice of fortune and blood and become a cripple in the service of my country, I little expected to meet the ungrateful returns I have received from my countrymen.”⁴⁰ He believed that Washington, during the court-martial, had withheld the unconditional support he merited, by maintaining a studious neutrality. Afterward, Washington pledged to Arnold that he would give him “opportunities of regaining the esteem of your country.”⁴¹ Unbeknownst to Washington, Arnold had by now established contact with Major John André, adjutant general of the British Army, and was prepared to assist Sir Henry Clinton in a secret plan to seize West Point. Peggy Arnold, having befriended André during the British occupation, was a full-fledged confederate of the plot. Heavily in debt, the mercenary Arnold brokered a rich deal for his treachery, charging the British six thousand pounds sterling and a commission in the British Army for delivering West Point into their hands.

In June 1780 West Point took on added importance. Washington feared that Clinton might return from Charleston with a hundred vessels and aim a deadly blow at the fortress. His worries were only compounded in July when Admiral Mar-riot Arbuthnot appeared in New York Harbor with sixty or seventy more ships. Washington swore he would do everything in his power to shore up West Point and other defensive posts along the Hudson River. At about this time Arnold rode up to Washington on the bluff at Stony Point and asked if he had “thought of anything for him.” When Washington offered him a “post of honor,” commanding the “light troops,” Arnold blushed and grew flustered. “His countenance changed and he appeared to be quite fallen,” Washington remembered, “and instead of thanking me or expressing any pleasure at the appointment, never opened his mouth.”⁴² When Washington met Arnold at his headquarters, his limp was unaccountably accentuated. Arnold had already impressed upon Washington’s aide Tench Tilghman that he could no longer ride horses for long or undertake active commands and indicated his desire for the sedentary post at West Point. “It then appeared somewhat strange to me that a man of Arnold’s known activity and enterprise should be desirous of taking so inactive a part,” Washington later reflected. “I, however, thought no more of the matter.”⁴³ Submitting to Arnold’s importunate wishes, Washington announced on August 3, 1780, that “Major General Arnold will take command of the garrison at West Point.”⁴⁴

That September, not realizing that Arnold was in league with the enemy, Washington enjoined him to improve West Point’s defenses. Arnold pretended to embark on a whirl of improvements at the fortress, while continually weakening them. He made it seem as if hundreds of men were hard at work when mere dozens were enlisted. When Washington alerted Arnold that he would pass through the Hudson Valley on the way to Hartford—“I want to make my journey a secret,” Washington stressed—Arnold relayed this letter to his British accomplices, listing places Washington would spend the night.⁴⁵ Had the letter not been delayed, Washington might well have been taken by the British.

While Washington was returning from Hartford, Major André, traveling under the pseudonym of John Anderson, slipped behind American lines to collect intelligence from Arnold, who handed him papers outlining West Point’s troop strength and artillery, along with the minutes of a September 6 war council sent to him by Washington. André tucked these tightly folded papers into his boot for safekeeping. Arnold also gave him a letter designed to smooth his way past sentries, which read: “Permit Mr. John Anderson to pass the guards to the White Plains, or below, if he choose. He being on public business by my direction.”⁴⁶ While returning to the British man-of-war Vulture, anchored in the Hudson, André was detained in Westchester County on September 23 by three American militiamen, who stripped him and unearthed the explosive documents. In vain, he tried to bribe his way to freedom. That André was elegantly dressed in mufti, outfitted in a purple coat trimmed with gold lace and a beaver hat, became damning evidence in the trial against him. Unaware of the significance of the documents found on him, Lieutenant Colonel John Jameson conveyed them to Washington with the following note: “Inclos[e]d you’ll receive a parcel of papers taken from a certain John Anderson, who has a pass signed by General Arnold.” André had asked to retain the papers, Jameson continued, but “I thought it more proper your Excellency should see them.”⁴⁷

Two days later, not yet having seen this letter, Washington awoke at dawn in Fish-kill, New York, and set off with a long train of aides (including Lafayette) and guards to breakfast with Benedict and Peggy Arnold. The couple occupied a roomy mansion on the east bank of the Hudson River, the former residence of Washington’s friend Beverley Robinson, who had raised a Loyalist regiment. En route to the house, which stood two miles below West Point, Washington made a detour to inspect several defensive positions along the river, occasioning banter from his young aides. Lafayette reproached Washington playfully, saying how the young men awaited their breakfast with the ravishing Peggy Arnold. Washington knew the coquettish charm she exerted over his men—he had known her for many years—and said gaily to his aides, “Ah, I know you young men are all in love with Mrs. Arnold . . . You may go and take your breakfast with her and tell her not to wait for me.”⁴⁸ Two aides, Samuel Shaw and James McHenry, went ahead with the message that the large party of guests had been delayed but would shortly arrive for breakfast.

For Washington, it was a surreal day of curious absences, missed hints, and odd anomalies that he did not piece together into a picture of outright treason. That he found nothing suspicious in Arnold’s behavior for so many hours showed his implicit trust in him. When Washington dismounted at the Robinson house at ten-thirty A.M., one of Arnold’s aides, Major David Franks, explained that his boss had been summoned to West Point on an urgent call and that Peggy Arnold lay abed upstairs. After a more solitary breakfast than anticipated, Washington boarded an awning-shaded barge, which ferried him across the Hudson to West Point, where he expected to be saluted by his host. But Arnold did not show up, and everyone professed ignorance of his whereabouts. The mystery only deepened as Washington scrutinized West Point’s defenses and was shocked by their decrepit state, which showed none of the strenuous attention promised by Arnold. “The impropriety of his conduct, when he knew I was to be there, struck me very forcibly,” Washington later said. “I had not the least idea of the real cause.”⁴⁹

Late in the afternoon a puzzled Washington was rowed back to the Robinson house. There was still no sign of Benedict, and Peggy Arnold remained incommunicado upstairs. As Washington rested in his room before dinner, Hamilton tapped on his door and laid before him a sheaf of papers, including the letter from Colonel Jameson. To his inexpressible horror, Washington set eyes on the war council minutes he had sent to Arnold, along with confidential information about West Point. Washington was thunderstruck. “Arnold has betrayed us!” he exclaimed. “Whom can we trust now?”⁵⁰ As he gave way to strong feelings, he struggled to get a grip on his emotions. From his reaction it is clear that he was innocent enough, or trusting enough, to find Arnold’s treachery almost inconceivable. The supreme betrayal had come not from Horatio Gates or Charles Lee or others long suspected of disloyalty, but from a man whom he had trusted, admired, and assisted. Despite a healthy dose of cynicism about most people, Washington had missed all the warning signs with Benedict Arnold.