Peggy Shippen Arnold was then dressing in anticipation of hosting a breakfast for Washington and his party. Possibly based on a brief discussion with her husband, she pretended hysteria in order to falsely convince General Washington and his staff that she had nothing to do with her husband's betrayal. The delay caused by her histrionics may have allowed Arnold time to escape, leaving Peggy with their infant son. Fearing for her safety, she traveled to Philadelphia to stay with her family. She also played the innocent when asked about her husband, even though she knew his whereabouts. Philadelphia authorities soon found a letter from André to Peggy written from British-occupied New York—the so-called "millinery letter"—and seized upon it as proof that Arnold's wife had been complicitous in the treason. That led the Supreme Executive Council of Pennsylvania to banish her from Philadelphia. In November 1780, her father escorted Peggy and her infant son to the shores of the Hudson where she boarded a boat to New York City to join Arnold.