Arnold promptly asked Congress to investigate the charges. He regarded this report of the committee as a vindication of his character; but he immediately urged Congress to act speedily upon the report. Instead of doing so, the report was referred to a joint committee of Congress and the Executive Council of Pennsylvania. They passed a resolution to refer some of the charges to a court-martial, to be appointed by Washington. When the charges were so referred, Arnold was indignant, but was compelled to submit. He urged prompt action, but a court-martial to try him was not convened until December following. They gave their decision on the 26th of January, 1780. The accused was acquitted of several of the charges, and of "all intentional wrong" in the whole matter of the other charges; but it was decided that, for "imprudent and improper conduct," he should be reprimanded by the commander-in-chief. This was done in the most delicate manner by Washington; but, as it implied a stigma upon his character, Arnold was exceedingly indignant. This act doubtless stimulated him in his treasonable undertaking, in which he appears to have been already engaged for fully nine months. Dr. Sparks says: "He [Arnold] had already made secret advances to the enemy under a feigned name, intending to square his conduct according to circumstances; and prepared, if the court decided against him, to seek revenge at any hazard." There appears to be clear evidence that overtures were first made by the other side, probably by Beverly Robinson,[25] to whom is attributed a letter given by Marbois, who was attached to the French legation at Philadelphia.[26] Be that as it may, it is known that correspondence between General Arnold and Sir Henry Clinton began so early as the spring of 1779. Arnold wrote in a disguised hand, and under the assumed name of "Gustavus." The tenor of the correspondence was of a commercial character, so as to mislead others. After the exchange of two or three letters, and with the impression that "Gustavus" was an officer of high rank in the American army, Clinton committed the task of carrying on the correspondence to Major André, who wrote over the signature of "John Anderson," in a slightly disguised hand. Not doubting that "Gustavus" was General Arnold, André probably wrote the letter to Mrs. Arnold in August for the purpose of making clear to her husband the name and character of "John Anderson" by means of his handwriting: [Illustration: I am in behalf of Mi'm ---- and Co. Sin your Obed. Hble Servant Mr. John Anderson Merchant Gustavus Fac-simile of Arnold's Disguised Handwriting.] [Illustration: Let me entreat you Sir to favour a matter interesting to the parties concerned. John Anderson Fac-simile of André's Disguised Handwriting.]