Indeed. Fox was a "US Agent" hand picked by Lincoln. He was a former naval officer, and had naval combat experience. He personally devised the plan for the union to bull their way into the harbor and offload troops, guns, and ammunition in direct violation of every pledge made to South Carolina. In one communique he even explained how his plan was based on a European naval battle that faced numerous shore batteries like that in Charleston, and that his plan would work on the same principles. The whole deal was deceit and dishonesty from the onset. South Carolina dealt in good faith, and received treachery in return.
The Daily Picayune of New Orleans picked up on Fox's duplicity and noted in its editorials:
With words of peace, they obtained admission into the fort for spies, who betrayed the confidence reposed in their honor, and with the pledge that his purpose was pacific, arranged there a plot for the introduction of armed succor. ... The betrayal of such a trust is the culmination of a long course of meditated duplicity in the Cabinet at Washington and is ample justification for no longer trusting either to their sense of honor or the sincerity of any professions they make if they desire to adjust the pending controversies in any other way but by an issue of force.Here terminates, in a disgraceful exposure, the juggle with which the Lincoln Cabinet have been practicing to deceive the public for the last six weeks.