Information of these facts, with a printed copy of the charges, reached Arnold at Washington's camp. On the following day he issued an address to the public, recalling his faithful services of nearly four years, and inveighing against the proceedings of the president and council; who, not content with injuring him in a cruel and unprecedented manner with Congress, had ordered copies of their charges to be printed and dispersed throughout the several States, for the purpose of prejudicing the public mind against him, while the matter was yet in suspense. In conclusion, Arnold informed the public that he had requested Congress to direct a court-martial to inquire into his conduct, and trusted his countrymen would suspend their judgment in the matter, until he should have an opportunity of being heard.
On the 16th of February, Arnold's appeal to Congress was referred to the committee which had under consideration the letter of President Reed and its accompanying documents, and it was charged to make a report with all convenient despatch. Arnold, in the course of January, had obtained permission from Washington to resign the command of Philadelphia, but deferred to act upon it, until the charges against him should be examined. About the middle of March, the committee brought in a report exculpating him from all criminality in the matters charged against him. As soon as the report was brought in, he considered his name vindicated, and resigned.
Whatever exultation he may have felt was short-lived. Congress did not call up and act upon the report, as, in justice to him, they should have done, whether to sanction it or not; but referred the subject anew to a joint committee of their body and the assembly and council of Pennsylvania. The report of the joint committee brought up animated discussions in Congress. Several resolutions recommended by the committee were merely of a formal nature, and intended to soothe the wounded sensibilities of Pennsylvania; these were passed without dissent; but it was contended that certain charges advanced by the executive council of that State were only cognizable by a court-martial, and, after a warm debate, it was resolved (April 3d,) by a large majority, that the commander-in-chief should appoint such a court for the consideration of them.
Arnold inveighed bitterly against the injustice of subjecting him to a trial before a military tribunal for alleged offences of which he had been acquitted by the committee of Congress. He was sacrificed, he said, to avoid a breach with Pennsylvania. In a letter to Washington, he charged it all to the hostility of President Reed, who, he affirmed, had by his address kept the affair in suspense for two months, and at last obtained the resolution of Congress directing the court-martial. He urged Washington to appoint a speedy day for the trial, that he might not linger under the odium of an unjust public accusation.
It was doubtless soothing to his irritated pride, that the woman on whom he had placed his affections remained true to him; for his marriage with Miss Shippen took place just five days after the mortifying vote of Congress.
Washington sympathized with Arnold's impatience, and appointed the 1st of May for the trial, but it was repeatedly postponed; first, at the request of the Pennsylvania council, to allow time for the arrival of witnesses from the South; afterwards, in consequence of threatening movements of the enemy, which obliged every officer to be at his post. Arnold, in the meantime, continued to reside at Philadelphia, holding his commission in the army, but filling no public office; getting deeper and deeper in debt, and becoming more and more unpopular. For months, he remained in this anxious and irritated state. At length, when the campaign was over, and the army had gone into winter-quarters, the long-delayed court-martial was assembled at Morristown. Of the eight charges originally advanced against Arnold by the Pennsylvania council, four only came under cognizance of the court. Of two of these he was entirely acquitted. The remaining two were:
First. That while in the camp at Valley Forge, he, without the knowledge of the commander-in-chief, or the sanction of the State government, had granted a written permission for a vessel belonging to disaffected persons to proceed from the port of Philadelphia, then in possession of the enemy, to any port of the United States.
Second. That, availing himself of his official authority, he had appropriated the public wagons of Pennsylvania, when called forth on a special emergency, to the transportation of private property, and that of persons who voluntarily remained with the enemy, and were deemed disaffected to the interests and independence of America.
In regard to the first of these charges, Arnold alleged that the person who applied for the protection of the vessel, had taken the oath of allegiance to the State of Pennsylvania required by the laws; and that the intentions of that person and his associates with regard to the vessel and cargo appeared to be upright. In regard to the second charge, while it was proved that under his authority public wagons had been so used, it was allowed in extenuation that they had been employed at private expense, and without any design to defraud the public or impede the military service. In regard to both charges, nothing fraudulent on the part of Arnold was proved, but the transactions involved in the first were pronounced irregular, and contrary to one of the articles of war; and in the second, imprudent and reprehensible, considering the high station occupied by the general at the time, and the court sentenced him to be reprimanded by the commander-in-chief. The sentence was confirmed by Congress on the 12th of February (1780).
The reprimand adjudged by the court-martial was administered by Washington with consummate delicacy. The following were his words: "Our profession is the chastest of all; even the shadow of a fault tarnishes the lustre of our finest achievements. The least inadvertence may rob us of the public favor, so hard to be acquired. I reprehend you for having forgotten, that, in proportion as you had rendered yourself formidable to our enemies, you should have been guarded and temperate in your deportment towards your fellow-citizens. Exhibit anew those noble qualities which have placed you on the list of our most valued commanders. I will myself furnish you, as far as it may be in my power, with opportunities of regaining the esteem of your country."