As they rode back to the Robinson house about noon they were met by Colonel Hamilton, who took Washington aside, and handed him the secret papers that had been found on André. At once the whole plot was clear. Washington sent Hamilton immediately to arrest Arnold, but the Colonel found that the man had already flown. Then the commander-in-chief told the news to Lafayette and Knox, and, saying how much he had always trusted General Arnold, added, “Whom can we trust now?” It was Lafayette who later tried to comfort Mrs. Arnold, when the full realization of her husband’s disgrace almost drove her to despair. And he sat with the other general officers at a court-martial in the headquarters at Tappan on the Hudson when John André, adjutant-general of the British army, after a fair trial, was convicted of being a spy and was sentenced to be hung. But Lafayette was a very generous judge, and wrote of André later, “He was a very interesting man; he conducted himself in a manner so frank, so noble, and so delicate, that I cannot help feeling for him an infinite pity.” The treason of Benedict Arnold prevented the invasion of Canada, and Lafayette saw no active service for some time. He spent the autumn in camp on the Hudson and in New Jersey, and part of the winter in Philadelphia. A number of French officers had gathered here, and they, used to the gayeties of the most brilliant court in Europe, added much to the amusements of the American capital. Every one liked the French guests, and the foreign officers, on their part, liked and admired their new allies. Sometimes the self-denying seriousness of the Americans, which was an element of their national strength, amused and surprised the gayer Frenchmen. One of the latter, the Marquis de Chastellux, told a story about Philadelphia in his volume of “Travels.” He said that at balls in Philadelphia it was the custom to have a Continental officer as the master of ceremonies, and that at one party he attended that position was held by a Colonel Mitchell, who showed the same devotion to duty in the ballroom that he showed on the field of battle. This Colonel saw a young girl so busily talking that she could pay little attention to the figures of the quadrille, so he marched up to her and said to her severely, “Take care what you are doing; do you suppose you are there for your pleasure?” Naturally the Marquis de Chastellux and his friends, fresh from the world of Marie Antoinette, where pleasure was always the first aim, had many a laugh at the people of this new world. But with the laugh there always went respect and admiration.