Has the existence of an assassination plot against Washington ever even been definitively proven? I'd always heard it described as one of many unproven rumors s

Has the existence of an assassination plot against Washington ever even been definitively proven? I'd always heard it described as one of many unproven rumors swirling around Hickey at the time of his execution. Hickey was officially charged at his court-martial with counterfeiting, mutiny and sedition, which are certainly serious charges, but not with any specific assassination plot. And the author's citation for his claim that Hickey was definitely involved with some kind of assassination plot rests entirely on the same breathless contemporary letter from Dr. William Eustis that you reference (which can be read in its entirety here: http://www.gutenberg.org/files/21990/21990-h/21990-h.htm#NO39 http://www.gutenberg.org/files/21990/21990-h/21990-h.htm#NO3...). One letter seems like an awfully slim reed to hang a charge like that off of.