https://www.ushistory.org/valleyforge/washington/vision.html
In the National Tribune, 1880, an article appeared giving an account of the "Vision of Washington" at Valley Forge. The account was told by a gentleman named Anthony Sherman, who supposedly was at Valley Forge during the winter of 1777-78. The story has been published several times.
Some people will say that it is substantiated by the fact that a copy of the account is in the Library of Congress. This argument of authenticity is misleading in and of itself. The Library of Congress has copies of anything published. That does not indicate accuracy of the content.
I am unaware of any eighteenth-century evidence that corroborates this story. The soldier mentioned as having a first-hand account of the "Vision," Anthony Sherman, was a soldier in the Continental Army. However, according to his pension application, written by him, he states that he was at Saratoga under the command of Benedict Arnold at the end of 1777 and only joined the main forces in 1778 in New Jersey just before the Battle of Monmouth.
Anthony Sherman wrote:
You doubtless heard the story of Washington's going to the thicket to pray in secret for aid and comfort from God, the interposition of whose Divine Providence brought us safely through the darkest days of tribulation. One day, I remember it well, when the chilly winds whistled through the leafless trees, though the sky was cloudless and the sun shown brightly, he remained in his quarters nearly all the afternoon alone. When he came out, I noticed that his face was a shade paler than usual. There seemed to be something on his mind of more than ordinary importance. Returning just after dusk, he dispatched an orderly to the quarters who was presently in attendance. After a preliminary conversation of about an hour, Washington, gazing upon his companion with that strange look of dignity which he alone commanded, related the event that occurred that day."George Washington's Vision"
This afternoon, as I was sitting at this table engaged in preparing a dispatch, something seemed to disturb me. Looking up, I beheld standing opposite me a singularly beautiful female. So astonished was I, for I had given strict orders not to be disturbed, that it was some moments before I found language to inquire the cause of her presence. A second, a third and even a fourth time did I repeat my question, but received no answer from my mysterious visitor except a slight raising of her eyes.
By this time I felt strange sensations spreading through me. I would have risen but the riveted gaze of the being before me rendered volition impossible. I assayed once more to address her, but my tongue had become useless, as though it had become paralyzed.
A new influence, mysterious, potent, irresistible, took possession of me. All I could do was to gaze steadily, vacantly at my unknown visitor. Gradually the surrounding atmosphere seemed as if it had become filled with sensations, and luminous. Everything about me seemed to rarefy, the mysterious visitor herself becoming more airy and yet more distinct to my sight than before. I now began to feel as one dying, or rather to experience the sensations which I have sometimes imagined accompany dissolution. I did not think, I did not reason, I did not move; all were alike impossible. I was only conscious of gazing fixedly, vacantly at my companion.
Presently I heard a voice saying, "Son of the Republic, look and learn," while at the same time my visitor extended her arm eastwardly, I now beheld a heavy white vapor at some distance rising fold upon fold. This gradually dissipated, and I looked upon a stranger scene. Before me lay spread out in one vast plain all the countries of the world — Europe, Asia, Africa and America. I saw rolling and tossing between Europe and America the billows of the Atlantic, and between Asia and America lay the Pacific.
"Son of the Republic," said the same mysterious voice as before, "look and learn." At that moment I beheld a dark, shadowy being, like an angel, standing or rather floating in mid-air, between Europe and America. Dipping water out of the ocean in the hollow of each hand, he sprinkled some upon America with his right hand, while with his left hand he cast some on Europe. Immediately a cloud raised from these countries, and joined in mid-ocean. For a while it remained stationary, and then moved slowly westward, until it enveloped America in its murky folds. Sharp flashes of lightning gleamed through it at intervals, and I heard the smothered groans and cries of the American people.